Linnaeus and the Breast

Humans have questioned where we belong in the natural world for centuries. Some still ponder today. Charles Darwin skimmed over the subject very briefly in his wonderful masterpiece On the Origin of Species outlining his theory of evolution through natural selection. Tantalisingly Darwin writes a one liner where humans may fit in; “Light will be thrown on the origin of man and his history”. Darwin’s close friend and supporter, Thomas Huxley, examines in detail the human species compared to other animals in his own masterpiece Man’s Place in Nature (1863). Typical of Huxley’s work, he provides clear and logical comparisons to other species, focusing on apes in particular. To introduce his comparison with animals, always eloquent, Huxley writes;

“The question of questions for mankind – the problem which underlines all others, and is more deeply interesting than any other – is the ascertainment of the place which Man occupies in nature.”

Huxley, Man’s Place in Nature. 1898 Edition. pg 77.

The famous image from Huxley’s Man’s Place in Nature demonstrating the similarities of the anatomy of the great apes.
(Image from here)

The answer for Huxley’s ‘question of questions’ is surprisingly laid bare in the classification of animals developed 150 years earlier. (Classification is simply organising life. All organisms on the planet are divided into a number of groups which place those with similar features into the same group.*) Of course Huxley talks about classification in Man’s Place in Nature clearly showing us how animals are organised and where humans sit in this classification.

The beginnings of the classification system we use today was developed in the 1700s by a Swedish chap who had a little fondness of breasts. Our story begins long before then, in the heat of the bustling city of Athens where the temples were full, the amphitheatres were packed and the wine filled amphorae were passed round carefree every evening.

Aristotle (384-322BC), the famous Greek philosopher, taught many noble men (including Alexander the Great), and his writings covered a ridiculously diverse range of subjects including politics, music, ethics, poetry and biology.

The great thinker looked at animals and plants and grouped them based on his own observations (looking at the way they move, a little bit of reproduction, and what they are made up of). For the first time, his work grouped animals together based on their similarities. He split the first group into two; ‘Blooded animals’ (basically animals with a backbone; the vertebrates) and ‘Bloodless animals’ (those animals without a backbone; the invertebrates). Aristotle broke the next categories down even further; life bearing (humans and mammals) and egg bearing (birds and fish). The classification didn’t stop there: it went on for some more levels each time grouping animals with similar features so that each time the groups contained less and less animals until it ended up with the individual. The old scholar used his groupings to show a ladder of the simplest organisms moving upwards to the highest, his ‘Great Chain of Being’. Much of this work set the basis for subsequent classification of the natural world.

A lovely marble bust of Aristotle showing rather chiselled features. (Image from here)

Aristotle’s work on animals and plants stuck around for around 2000 years, before there was a renaissance in looking at the life around us. This mainly began with new attempts at classifying plants because of their important uses in medicines. The Italian botanist, with a rather well trimmed beard, Andrea Casalpino (1519 – 1603) was one of the first to look at the features of plants and use the similarities to classify them. He wrote a somewhat large and, to many people, fairly quite an un-thrilling piece of work describing and classifying over 1500 species based on the structures of the seeds.

Soon after there was an obsession to classify more. Another botanist, this time from Switzerland and a much more elaborate beard, Gaspard (or Caspar) Bauhin (1510-1624) wrote an enormous book on plants. Titled Pinat theatre botanici (Illustrated exposition of Plants), he describes and classifies over 6000 species. Regardless of the slightly limited readership, the wonderful thing about this book was that Bauhin grouped similar plants together, and he introduced the method of using genus and species in his classification; plants which Bauhin thought were similar were placed in the same genus and then each different individual plant was then given their own species name. This method of naming organisms using a genus and species is still used today.

These passionate and mildly obsessed bearded gentlemen had begun to try to arrange life by giving them Latin names. Over the years, there were several attempts with a variety of different groups added and moved around. John Ray (1627 – 1705) was an (unbearded) English man who attempted to classify a huge number of species (over 18,000 plants in one publication!). Ray’s system was thorough but he appeared to combine different characters of different plants in his ‘organising’.

With such a huge variety of different ways in organising life and different names being given to the same plant, there needed to be a standard that would be used the world over. Enter a man who was rather fond of breasts.

Carolus Linnaeus, also known as Carl von Linné, (1707-1778) was a clean shaven Swedish naturalist who gave lectures in botany at Uppalsa University. He had a pure lust for studying as much as he could about the natural world. Linnaeus developed his Systema Naturae (System of Nature) in 1735 as a twelve page list of organising the plants, animals and minerals he knew. His cravings were not satisfied with this work. For the next 31 years he had developed several editions resulting in his monstrous 12^th Edition in which he organised and classified over 12,000 different species. All the animals and plants in his Systema Naturae were given binomial names (genus and species) and this set the precedence for future work on naming life. Linnaeus’s system has been widened, adapted and changed over time, but the basic idea is still the same.

Carolus Linnaeus (or Carl von Linné (1707-1778). A Sweedsih naturalist who was well kept and developed the system of classification we use today. (Image from here)

It is the famous 10^th Edition where we get a first glimpse of the breast. Over 2000 years earlier, Aristotle had grouped all animals on four legs as Quadrupedia (including mammals, most reptiles and a lot of amphibians). Makes sense, as they all have four limbs. There were a few problems with the term Quadrupedia which naturalists were not too keen on; for example, manatees only have two ‘hands’, chimpanzees have four ‘hands’, and humans have two feet and two hands. But Linnaeus sorted this out in a little more detail. Along with some classes from the old philosopher, he developed some new ones for his classification resulting in six classes; Mammalia (mammals), Aves (birds), Amphibia (reptiles and amphibians), Pisces (fish), Insecta (insects and arachnids) and Vermes (worms). This allowed for large groups which shared similar features to be grouped in these classes. For example all species of Owls were placed in the same Order (Strix), and this Order was grouped with all other Orders of birds under the Class Aves.

Wonderful. And the link to breasts is in there too. But this will need a little explaining, as it may appear that I have some weird geeky fetish to taxonomy where systematics is the nipple that I enjoy tweaking. Although many of us do get excited about fantastic science, it is not really a fetish. Not really. I don’t have a room fully of pictures of taxonomic trees on my walls in front of a lovely old oak desk covered in pinned insects, study skins and a delightfully old microscope. One day perhaps I will. But for now, my little ‘office’ under the stairs will do.

Linnaeus unveiled the breast in the new class he developed; Mammalia; literally meaning ‘of the breast’. He could have used a different term for this group of animals because there are six little features that you can look at in any animal anywhere that determines whether or not it is a mammal;

1. An articulated jaw. All mammals have one bone in their lower jaws, the dentary (two dentary bones on the left and right side, which are fused together at the chin). Reptiles have three bones in their lower jaws.
2. Three ear bones. The lovely little incus, mallus and stapes are the smallest bones in the human body. These three tiny, beautifully shaped bones were once three bones in an early reptilian ancestors head. Three bones, the quadrate, articular and angular in one group of very early reptiles shrank, moved, and became vital in amplifying sound in the animal. This took a long time, and many generations and mutations; each change being useful and passed onto the next generation. We know this because otherwise we wouldn’t laugh and weep at a magnificent performance of the beautiful Madame Butterfly.
3. Mammary gland. The milk producing glands which are functional in the females and only for a short period of time. This can be with the help of a nipple, or like the platypus and spiny anteater lactating milk on your chest is enough for the little ones to lap up.
4. The aortic arch (a main artery in the heart) bends to the left. This is a very efficient way of transporting oxygen rich blood round the body as the heart pumps.
5. Cheek teeth with divided roots. All mammals have the teeth at the back of their mouths (the molars) which have at least two roots holding the tooth into the jaw. Mammal teeth vary for different uses; the flat incisors at the front for nipping grass or flesh; the sharp canines for piercing prey or fighting other males; the pointy pre-molars for slicing or grinding; and the back molars to really slice or grind. Fish, reptiles and amphibians only have the same type of tooth throughout their mouths and one root.
6. Hair or fur. Mammals are the only animals that have ‘true’ hair which covers their bodies at some point in their lives. The hair grows from skin cells, called follicles, with the little protein keratin.

The term Mammalia derives from the Latin word mammae, referring to the breast or nipple as appose to the actual milk producing glands (the mammary glands). It is interesting that Linnaeus focused on a female feature to name this large group of animals. Some animals in this Class do not have breasts or nipples; such as the wonderfully enigmatic platypus and bizarre quirky spiny anteaters, which are the only living members of the egg laying mammals, the Monotremes. These creatures have all the features of a mammal (three ear bones, single jaw bone, hair, produce milk through mammary glands). But they lay eggs. And they don’t have nipples. (The Monotremes secrete milk from their mammary glands, which the youngsters lavishly lap up.) Because of the features they share with all other mammals, apart from laying eggs, these beautiful creatures do belong to the Class Mammalia.

So really the nipple or breast isn’t actually a defining diagnostic feature of Mammalia. For those mammals that do have nipples, generally both the females and males have them. This is simply because the nipples form in the developing foetus before the sex is developed; for a while in the womb the little developing animal is sexless. (There are exceptions where some male mammals don’t have nipples, for example, horses and some rat species). The true feature of a mammal is not whether it has a nipple or breast, but it is an animal where the females produce milk to nourish their young.

As a little aside, it is delightfully curious that only our species uses the breast for enjoyment during nights of passion. Many women, and men, find the nipple and the surrounding area to be an extremely sensitive and pleasurable part of the body. The amazing and complex evolution of the sex lives of our species is for a future post, but the breast clearly played an enchanting role in our species enjoying and prolonging the sex for as long as we do.

Back to Linnaeus and the breast. Why would he have focused on the breast? He could have easily chosen another term, such as Pilosa (the hairy ones), Aurecaviga (the hollow eared ones), Lactentia (the lactating ones) or Sugentia (the suckling ones), Tresauremos (those with three ear bones), Unamaxillia (one jawed ones). By naming the Class of hairy lactating creatures Mammalia, he created a simple link to include one certain species within his classification; us.

The 10^th Edition which saw the introduction of the new term Mammalia, also saw the first time of including humans within the System of Nature; he gave humans the scientific name Homo sapiens. By giving humans a scientific name and including them within his classification, Linnaeus had linked humans with the animal kingdom. Humans were placed along with apes, monkeys and sloths in the Order Primates. (Sloths are no longer within the Primates, but are in a new Order Pilosa along with anteaters.) Of course, there was uproar! Humans in the same group as monkeys!! Oh, to be a fly on the wall as the great scientific folk read this for the first time! But Linnaeus was clever. He showed there was no way out from classifying humans along with other animals; humans share many of the same features as all mammals. One of these features which there was certainly no denying was the breast.

Historically, breast feeding has been seen as linking humans closer to the animal kingdom quite simply because other animals do it, resulting in women seen to be closer to the animals than men. Aristotle noted how women gave birth to live young and nursed their young, just like many other animals. Confused by bodily functions, many people thought that menstruation and lactation were linked; Aristotle believed that the menstrual fluid transformed into the fluid for nursing the young after giving birth. This complete lack of understanding of biology is what we would see today as completely bonkers. Amazingly until the mid-1700s Aristotle’s view on things was believed to be true (that’s 2000 years of silence in the study of science!).

The wonderfully large nipples (or teats) of a female goat with her young close by. The nipples are very large so the baby goat can get easy access.
(Image from here)

The choice of the term Mammalia is interesting because the names of all the other groups focus on features shared by all animals in that group. For example, the Phylum Arthropoda means ‘jointed legs’, which all animals (both male and female) in this group have. The Class Amphibia means ‘both lives’ as all these slimy creatures in this group live in and out of water. Mammalia however, focuses on the female of the species. By giving the Class the name Mammalia automatically shows that humans are no different and fit within the classification.

Mr Linnaeus probably thought about breasts for quite some time with this strategic move. With the breast proudly exposed as the defining trait for the group, humans could be included. And here, he was very clever again. He named our species Homo sapiens meaning ‘man of wisdom’ which was a very proud and masculine name. Linnaeus made sure the breast and the woman linked with other animals, and ‘man’ stood alone. Like many in the 1700s, and even 1800s, he still thought that ‘man’ was special, one of God’s greatest creations (Linnaeus himself was a Creationist). So humans fitted in his classification, but were separated from the ‘lower animals’ by the species name he gave. Very clever.

The breast: one defining feature to link humans with the rest of the animal kingdom. Although Huxley’s ‘question of questions’ wouldn’t be asked for another 150 years, Linnaeus had already began to answer it. Linnaeus had wanted to satisfy his lust by organising nature and by doing so he grouped together animals with similar features (ie. animals that were closely related). It was never his intention to demonstrate any evolutionary relationship. His classification however beautifully illustrates the wonderfully diverse tree of life and how all organisms reveal clues to their evolutionary past.

This Class of animals, the beautiful and varied group of mammals, is absolutely extraordinary! One feature in particular is a true marvel of the natural world; sweat glands in one particular part of the body have been modified to produce milk and secrete it through contractions of ducts. Truly remarkable! Only mammals can do this. And this is the real beauty of these creatures. The dinosaurs didn’t breast feed their young; mammals did.  

The Class Mammalia does not demonstrate that women are closer to animals than men – this is an ancient idea that should have faded into dust. Quite the contrary. It shows the importance of females without which the Class would not exist. This is the reason the breast proudly sits so high up, defining this Class of fury, sweaty animals. And quite rightly so. One of the most beautiful features that has evolved in nature has now been immortalised as the defining feature of a very diverse and amazing group of animals we belong to; the mammals.

References;

Huxley, T. H. 1898. Man’s Place in Nature and other Anthropological Essays. New York. D. Appleton and Company.

Schiebinger, L. 1993. Why mammals are called mammals: gender politics in Eightieth-Century Natural History. The American Historical Review. Vol. 98. No 2. pp.382-411.

 

*The world of organisms is divided into a number of groups which place those with similar features into the same group. All animals belong to the Kingdom Animalia. These are then split into different Phylum (for example, those with a backbone (vertebrates) are placed in the Phylum Chordata). This Phylum is divided into 6 different Classes; all the birds for example are in the Class Aves, and all the mammals in put in the Class Mammalia. Each Class is then divided further with a number of Orders; all bats are in the Order Chiroptera and all cats, dogs, bears, walruses, seals, racoons and skunks are in the Order Carnivora. This is not the end! There is another divide under Order, the Family; this is where the groups become more closed and specialised. For example, all the species of kangaroos are in the Family Macropodidae and al the chimps, gorillas, orang-utans and humans are in the Family Hominidae. The penultimate group level is the Genus. Here there are fewer organisms in this group, sometimes there can be on animal in this group, or sometimes ten. The final group is the species. This is where the individual animal is named, for example all humans belong to the Genus and species Homo sapiens where as all blue tits belong to the Genus and species Cyanistes caeruleus.

From Shanklin

In 2009 the world embraced Darwinmania. The year was momentous. It celebrated the 200^th birthday of Mr Charles Robert Darwin and, coincidently, the 150^th anniversary of his most famous work under the slightly elongated and rather mouthful of a title On the Origin of Species by means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life. Fortunately this is known to most people today simply as On the Origin of Species.

Everyone was mad for a slice of Darwin. And why not? His life was interesting and we like interesting stories. He went to Edinburgh University to study for a medical career, only to cut it short after two short years. At a loss young Charles was encouraged by his father to go to Cambridge and gain a degree in Theology so he could become a clergyman (he passed with flying colours; a small irony enjoyed by many people). At the age of only 22, he travelled on-board HMS Beagle as the ships naturalist. For over 5 years he crossed oceans to new lands and discovered beautiful and exotic creatures never seen before by (European) human eyes. After returning back to England, he wanted to get married so wrote a list of pros and cons (who hasn’t?), and then married his cousin. He worked hard on his ‘mystery of mysteries’ and after 21 years of gathering information on it, he published his ‘essay’ in a book over 500 pages long that would shake the very foundations of the Vatican itself.

It made for an interesting year. The media reported several news stories about new research based on Darwin’s work, events and a plethora of science related stories. Several popular science books were released. An old mast ship, the Stad Amsterdam, set sail from Plymouth on 1^st September 2009 for a four month voyage following the route of HMS Beagle. Museums across Britain, and the world, used their own unique and fantastic natural history collections to tell their stories about Darwin, his life and work through displays and exhibitions. Embarrassingly, the Church of England jumped on this bandwagon by issuing an apology to Darwin “for misunderstanding [him] and getting our first reaction wrong, encouraging others to misunderstand [him] still”. A bizarre statement indeed.

For such an important year with a diverse amalgam of high profile events, exhibitions, and talks happening across the world, it was inevitable the film industry would join in for a large piece of the cake. Creation is the screenplay based on the book Annie’s Box by Randal Keynes. The film re-tells Darwin’s story of his own struggle to finish On the Origin of Species whilst effortlessly flashing back to his earlier life, including one event which affected him until his death; the loss of his eldest daughter Annie to scarlet fever. Apart from Darwin being portrayed as a little bit bonkers by hallucinating and talking to his deceased daughter, my major qualm was the characterisation of Thomas Henry Huxley.

If you have seen the film, there are a few scenes with Darwin talking to his two friends, the botanist, Joseph Hooker and the biologist, Thomas Henry Huxley. Played by the brilliant actor Toby Jones, Huxley is portrayed as an incredibly infuriating unlikeable character. He is short (both in stature and in temper), impatient and somewhat aggressive in his tone. Unfortunately Huxley’s personality acted out in these few short scenes is the general perception of this great man. Popular science books and books about Darwin will all mention Mr Thomas Henry Huxley, and most will describe him as a man who was egotistical, ready to fight Darwin’s cause, and had the wondrously fearsome title of Darwin’s Bulldog.

(A day before On the Origin of Species came out, on 23^rd November Huxley famously wrote to Darwin “[the chapter on the incompleteness of the fossil record may cause you] considerable abuse and misrepresentation…I am sharpening up my claws and beak in readiness.” Although Huxley wasn’t immediately taken with the theory of natural selection, he was keen to use the opportunity of the book to promote science in an attempt to take it out of the Dark Ages, away from the tight grip of religion. Back then much of science was used to show God’s great design in the world and Huxley saw this as detrimental to the progress of truth.)

The wonderful face of Huxley. Stern, focused, sexy, and unbelievably amazing sideburns. (Image from here)

Huxley was a bloody intelligent chap. His tongue was as sharp as his pen. But he didn’t spend his whole life battling the great demons of evolution and sending them back down to Hades. His real expertise, and real love, lay in studying the function and anatomy of animals (how animals worked) and he studied the relationships of many animals from jellyfish to dinosaurs. Huxley was someone who wanted to see the evidence for himself; if he read an article about a structure in an animal, he would go and dissect that animal so he could actually see it for himself. He was at home at his dissecting table!

In the mid-1800s science was mainly learnt by the affluent and jobs were dependent on knowing someone else in the inner circles rather than on merit. Super keen to make science less of a niche, the enthusiastic Huxley was instrumental in promoting science to the public by developing a series of lectures for the ‘working man’. These were incredibly popular and provides one of the earliest examples of communicating up to date science accessibly to the public. Huxley was also instrumental in helping shape Britain’s education system by developing the national curriculum to include the sciences for the enjoyment of every child.

As Huxley’s reputation grew he inevitably undertook more work. He was incredibly dedicated to work and often worked too much. But he always made sure he had time for his friends and family. Along with Joseph Hooker, Thomas Huxley was one of Darwin’s dearest and closest friends. He would often go with his family and spend time at Darwin’s home in Kent, especially as Darwin was very adverse to travelling to London. Huxley would update Darwin about the latest news in the scientific circles, and the two families always enjoyed time together.

Deep down Thomas Huxley was a devoted and caring family man. He had met his wife Henrietta (Nettie) Heathorn in Sydney in July 1847 when he was a young 22 year old assistant surgeon on-board HMS Rattlesnake. Thomas was drawn to sweet Henrietta’s confident and practical side (she had moved to Australia when she was 17 with her father and half sister and relished in the wilderness of the bush along with the challenges of living somewhere so wild). Surprisingly, the two young lovers had a lot in common; they shared  very similar views, they both loved classic literature and discussed it at length, and they both spoke German (Huxley was self-taught, and Nettie lived in Germany for 2 years). Nettie was a very bright girl, brighter it seems than any other Thomas had met before, for it was not her looks that melted his heart;

“Then as to the face, I really dont know whether she is pretty or not…her personal appearance has nothing to do with the hold she has upon my mind, for I have seen hundreds of prettier women.”

(Quote from McCalman, I. 2009. Darwin’s Armada. Pocket Books. page 173)

This photograph was taken in 1857,two years after her marriage to Thomas. Nettie was both intelligent and pretty. (Photo from Huxley, J. (Ed.) 1935. T. H. Huxley’s Diary of the Voyage of H.M.S. Rattlesnake. Chatto and Windus, London)

Probably not really the most flattering of comments anyone would want to hear (nor did he imagine for hundreds of people to read it!!), but cupid struck, and struck hard. Hettie was a pretty young lady, with soft smooth skin and a serious look about her. He fell in love with everything about this young, confident lady. He was so smittened that he proposed to her three months after they first met. Their engagement however was to last much longer than their courtship. For three years the two were engaged while Huxley and HMS Rattlesnake surveyed the North Australian and New Zealand coast, only seeing each other fleetingly. Every second they spent together was treasured. Huxley arrived back to England in 1850, and it would be another five years before they would finally marry on 21^st July 1855.

32 years later, a tired over-worked 62 year old Thomas Huxley picked up his well used pen, the blunted nib ran across the page as he wrote to his wife. 32 years of marriage was 33 years of his scientific career. He had postponed marriage until he was financially secure in a scientific job (which he finally got 4 years after returning back to England, as Professor of Natural History at the Royal School of Mines). In 33 years, Thomas Henry Huxley had become one of Britain’s, possibly the world’s, most influential and respected scientists.

Although Huxley retired from his main work when he was 60, he was still an active member of several scientific societies and wrote numerous articles. His wife and his friends regularly encouraged Thomas to take holidays and get away for a few weeks. One of the places he stayed was the calm, small village of Shanklin on the Isle of Wight. The thin higgledy-piggledy roads cut through solid stone cottages with thick bundles of thatching blanketing the roofs. The cottages themselves bulge outwards as if the Cursed Giant himself from ancient folklore had once walked through and decided to rest his large behind for a few moments on the soft thatching after a big feast of small children.

It was here, in the spring of 1887, that Huxley wrote his wife a poem allowing us to see a rare glimpse into Thomas Huxley the husband;

From Shanklin

Dear wife, for more than thirty years

Have you and I, hand clasped in hand,

Sometimes all smiles, sometimes in bitter tears,

Wended our way through the strange land

Of living men; until silvering hair,

And graver mien and steps more slow,

Adown the stand of age we fare

To the sill ocean, out beyond time’s flow.

True wife, housemother, worn with many cares,

Love’s afterglow shall brighten all the years

That yet are ours; and closer still shall be our clasp

Of hands, until they nerveless fall and cease to grasp.

T.H. Huxley

1^st March 1887

Thomas and Nettie in 1882. Nettie looks slightly camera shy and the photo doesn’t convey the couple’s radiance. (Photo from Huxley, J. (Ed). 1935. T. H. Huxley’s diary of the Voyage of H.M.S. Rattlesnake. Chatto and Windus, London. Pg. 316.)

Thomas Henry Huxley is not known for his romantic side. But he was dearly romantic to his Nettie. He loved and respected her more than anything else. The couple supported each other through incredibly tough times, both professional and personal. She was also a rock to Thomas from the very beginning; she had supported him when he was out at sea on HMS Rattlesnake when he had quite a severe breakdown – her letters were the only thing that kept him sane.

A poem to your wife after 32 years of marriage is a beautiful present. It is also a thoughtful present; Nettie loved poetry and wrote a lot herself (see the further reading at the end of this post). He acknowledges that they are getting old, and that one day they will both be gone, but the beautiful prose lets his wife know how the radiance that their love brings still glows strong. Huxley’s portrayal in books, and in the film Creation, is often one of arrogance. He was confident in his work (because he knew he was right!) but he also knew his wife was an equal, and the poem acknowledges the hard work she does and respect he has for her. Not many men in the 1880s would write these romantic, reverential, caring and soft words to their wife. Thomas and Nettie were made for each other.

From Shanklin reveals  Huxley’s softer side (if only Owen knew!). He was a loving husband, still deep in love with his wife after 40 years together. In public Thomas Henry Huxley was seen to be a fierce man not to be challenged, but in private Thomas was a devoted and passionate husband. Behind closed doors, Mr Darwin’s Bulldog was a soft cuddly labradoodle.

Further reading;

Huxley, H. 1913. Poems of Henrietta Huxley. With three of Thomas Henry Huxley. London. Duckworth & Co.

Keynes, R. 2001. Annie’s Box: Charles Darwin, his Daughter, and Human Evolution. Fourth Estate. London.

McCalman, I. 2009. Darwin’s Armarda. Pocket Books. page 173

For a brief life of Thomas Henry Huxley, well worth reading Chalmers Mitchell, P. 1913. Thomas Henry Huxley. A scketch of hsi life and work. Methuen & Co.