Wednesday, 16 August 2017

Foetus or fetus?

Human Fetus drawn by Leonardo da Vinci
There was a recent spate of tweeting about the correct spelling in British usage of fetus - or foetus. As the Oxford Dictionary makes clear, the spelling foetus has no etymological basis.

A similar debate 50 years ago was initiated by James Dixon Boyd and William James Hamilton in connection with the first edition of their influential textbook Human Embryology (previous post). This was in the BMJ. Coincidentally Bernard Towers (later Professor of Anatomy and Pediatrics at UCLA) raised the issue in Arch Dis Child. Earlier, Lionel Everard Napier had argued for "fetus" in The Lancet.

The thrust of their arguments was that "fetus" was the only spelling in use until 600 A.D., "foetus" being introduced by Isidorus of Seville on the basis of an erroneous etymology.
Statue of Isidorus of Seville in Madrid
Photo by Luis Garcia CC BY-SA 2.5
Boyd and Hamilton solicited opinion on the subject and the resulting letters fell out 5 to 1 in support of "fetus." Among the supporters was J.H.M. Pinkerton, later Professor of Midwifery and Gynaecology in Belfast. The counter argument, "Foetus is a word of respectable antiquity and lineage," was advanced by Hugh Gault Calwell who is known to have been skilled in Greek and Latin. Sadly, when Human Embryology appeared, it used "foetus" rather than "fetus."

References: BMJ 1967 (5337): 425, (5539): 568, (5540): 631, Arch Dis Child 1967; 42:224, Lancet 1952; 260: 885-6.

Monday, 7 August 2017

From antelope placenta to the chi square distribution

The Four-horned Antelope (Tetracerus quadricornis)
Philip Sclater The Book of Antelopes 1894
Despite its appearance, this Indian species is not a true antelope, but belongs to the subfamily Bovinae. Its placenta was described in 1884 by Raphael Weldon then a Scholar of St John's College, Cambridge.
Gravid uterus of the Four-horned Antelope
Weldon Proc Zool Soc London 1884
There was a fetus in each horn and Weldon was struck by the relative paucity of placentomes (30 and 22, respectively).
One extremity of the chorion of the Four-horned Antelope
Weldon Proc Zool Soc London 1884 
Weldon thought the interplacentomal regions resembled the diffuse placenta of the pig. This may have been overinterpretation. There seem to be no subsequent descriptions of placentation in this species.
The Nilgai (Boselaphus tragocamelus)
Rufus46 (Wikimedia Commons) CC BY-SA 3.0
Together with the Nilgai, the Four-horned Antelope forms its own tribe. Benirschki examined a couple of Nilgai placentas (here). He did not find an unusual number of cotyledons but remarked they were not as neatly arranged in rows as in other species. So perhaps Weldon was on to something.

Raphael Weldon is not remembered for his placental research. He became a marine biologist and was professor of Zoology first at University College London then at Oxford. At UCL he collaborated with the mathematician Karl Pearson and founded the science of biometrics. Famously, he rolled a set of 12 dice no fewer than 26,306 times. The results showed a bias towards fives and sixes (more here). These data were used by Karl Pearson in the latter's seminal paper on the chi-square statistic.