An investigation of some of D'Arcy Thompson's correspondence

Heather Dickinson and Barbora Cernokova

Correspondence III

Heilmann did not waste any time in responding to D'Arcy's request. His delight at being asked to contribute to D'Arcy's work shows the high regard in which he held it and also D'Arcy's reputation at the time. This letter from 9th April 1915 (ms19139) also demonstrates Heilmann's incredible modesty. Heilmann mentioned how he planned to use D'Arcy's method of transformation within his own work The Origin of Birds to construct the Pro-Avis (a hypothetical intermediate step in the evolution of dinosaurs to birds). Even before publication, D'Arcy's work helped to capture the imagination of and inspire others. It is thanks to this vital communication and D'Arcy's ever expanding web of correspondence that his theory of transformations was able to flourish and grow.

The next letter (ms19140) was sent on 30th June 1915 from D'Arcy to Heilmann along with a copy of his newly published paper Morphology and Mathematics. At this time D'Arcy had already begun work on On Growth and Form and he again enlisted Heilmann's help in producing drawings of his specimens. He suggested Heilmann illustrate the method in a case study of some group of animals, for example looking at the evolution of the skull of a human from the skull of an ape or early human. However he understood the difficulties with this particular study and this is discussed in more detail in later correspondence. An easier option, D'Arcy claimed, would be some group of mammals such as the Equus family. This is the route down which Heilmann had more success leading to his work being used in On Growth and Form. There is in fact an entire section of the book dedicated to skulls of mammals.

D'Arcy stated at the end of the letter that he was sending copies of his paper to "Professor Jungersen, Professor Boas, and some other friends in Copenhagen". This again illustrates just how wide his correspondence network truly was. D'Arcy had friends all over the world, a feat he no doubt achieved thanks to his talent for languages.

In his response from 13th July 1915 (ms19141), Heilmann thanked D'Arcy for his paper and agreed to carry out more work for him to be used in On Growth and Form. At this time he was away working on his artwork in the Danish countryside so did not have time for more thought on the matter. However, he did suggest that "the Equidae, the Rhinoceratidae and the Anthropoids would present excellent applications of your method". Skulls of Equidae and Rhinoceratidae are examined in On Growth and Form. Despite the difficulties with early humans a comparison of a human skull with that of a baboon and a chimpanzee are also illustrated. Heilmann clearly had made an impact on D'Arcy and D'Arcy respected him so much that he included his suggestions within his book.

Within the letter Heilmann also requested more copies of Morphology and Mathematics. This demonstrated the interest surrounding D'Arcy's work and the importance that Heilmann placed upon it.