Karl Pearson and Adelaide G. Davin 
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'nothing else than the ligaments of the articulations, or the firm tendons of strong 
' muscles, or both, become bony by the violent compression they suffer in the 
'situation they are.'" {Anatomy of the Bones, Edinburgh, 1726, p. 337.) 
It is true that this statement of Nesbit's, notwithstanding its definiteness and 
perspicacity, has been questioned somewhat cavalierly by Gruber*. He says that 
for many yeai's he examined the cadavers of embryos in last month, of new-born 
children in considerable number and of several children one to seven years old, and 
never found in the tendons of M. gastrocnemius a cartilago hyalina or fihro-cartilago. 
He does not state the exact numbers and appears to hold that Nesbit asserted the 
existence of orthosesamoids, whereas Nesbit as we read him is speaking of pre- 
figurations. Yet Gruber did himself find the hyaline cartilage elements in the 
tendons of puppies at birth where the fahellae later develop, and notes that the 
lateral ossifies first (at about six months)f. He does not state how many embryos 
and children he examined, and it is clear that as at least 90 " j ^ of adults exhibit no 
fahellae, it is quite conceivable that Nesbit may have found the prefigurations and 
Gruber not. But the fact that prefigurations are found in puppies and kittens, and 
the additional fact that not all sesamoids are associated with intensive stress while 
many regions of intensive stress are not associated with sesamoids J should be enough 
to dismiss this hypothesis, were it not that its supporters can appeal, as has been 
done in the case of femoral facets, to the principle that acquired characters are 
inhei'ited, a haven ready for the supporters of production by use, and one where the 
difficulty of demonstrating a negative — other than by Occam's Razor methods — 
leaves them in comparative security. 
Perhaps the most effective ejectant is the appeal, such as we hope to make in 
this paper, to the facts of the evolution of the sesamoids. Pfitzner, who was a strong 
opponent of the intensive stress hypothesis, not only cites Nesbit's results, but cites 
the case of the Marsupialia, and figures the Wombat, of which he writes : 
Wenn man annehnien miisste dass Gebilde von so reicher Formenentfaltung wie diese Epi- 
perone (so mochte ich sie nennen) beim Wombat jederzeit als "Product entziindlicher Reizung" 
oder dergl. neu entstehen konnten, so wiirde man bald jede wissenschaftliche Bearbeitung des 
Skeletsystems als ein aiissichtloses Unterfangen erkliiren musseii§. 
The reader who wishes to appreciate the full force of Pfitzner's argument should 
examine our Plate V, Fig. 13. It seems unanswerable as far as the Marsupials are con- 
cerned. Can we look for any evolutionary links between Pfitzner's "Epiperone," the 
" parafibula " of the Marsupials, and the sesamoids of the knee-joint of higher types ? 
For Pfitzner the source of the sesamoids is the same as that of any other bone 
of the skeleton, i.e. the force of heredity ||. He distinguishes as we have seen between 
* Gruber, p. 1.3. 
t Gruber, p. 57. We have ourselves found them, as well as the cyamella lateralis, prefigured in 
puppies at birth, and the Uvo fahellae and the cijarnella in kittens at birth. 
X Why should man and the greater anthropoids have lost their fahellae while they are universal in 
the lesser apes? The "stress"' has hardly disappeared. 
§ Pfitzner, S. 586. 
II Pfitzner, S. 535 and S. 563. 
