ON THE SESAMOIDS OF THE KNEE-JOINT. 
By KARL PEARSON, F.R.S. and ADELAIDE G. DAVIN, B.Sc. 
PART IL EVOLUTION OF THE SESAMOIDS. 
PAGE 
(8) Further Remarks on Origin of Sesamoids . ■ . • • 350 
(9) Carnivores .......... 351 
(10) Ungulates 353 
(11) Pinnipedia .......... 355 
(12) Ohiroptera 355 
(13) Insectivores 356 
(14) Rodents 357 
(15) Primates 360 
(16) Edentates 366 
(17) Marsupials 371 
(18) On Changes in the Muscular Attachments of the Knee-Joint . 376 
(19) Monotremes 383 
(20) Centre of Ossification' of Fibular Crest in Monotremes . . 384 
(21) Birds 387 
(22) Reptiles 389 
(23) Amphibia 391 
(24) Conclusions . , . 392 
Description of Plates (Part II) 396 
(8) Further Remarks on Origin of Sesamoids. 
In the first part of this paper attention was drawn to Gruber's statement that 
the sesamoid invariably arises from hyaline cartilage. We cited our own work as 
supporting this view and a considerable number of further sections made since 
entirely confirm it. We do not think it needful to publish the drawings made from 
these sections — they all show the same hyaline structure ; and we now hold with 
Gruber that no thickening in the tendons of M. gastrocnemius or M. popliteus 
should be classed as a hemisesamoid unless it shows this hyaline structure*. Every 
* Another matter of some interest is elucidated by our sections. Lunghetti (Internationale Monat- 
schrift fi'ir Anatomic itnd Physiologie, Bd. xvi. § 47) following Gillette in his classification of sesamoids 
into peri-articular and intratendinous claims to have shown that the origin of the peri-articular 
sesamoids is totally diiJerent from that of the intratendinous. We have already (p. 156) criticised 
Gillette's classification ; it does not seem to us in accordance with the evolutionary origin of the 
fahella lateralis and the cyamella, both are ultimately peri-articular in origin, and our sections seem to 
show that Lunghetti's view is erroneous. He asserts that the peri-articular are prefigured by hyaline 
cartilage which can be noticed in the foetus with the form of the definite bone. With this we are in 
agreement ; the sections of the metatarsal sesamoid in the human foetus (p. 159) demonstrate it. 
Lunghetti further asserts that the intratendinous only appear in the adult in the middle of a fibrous 
tissue which chondrities a sliort time before ossification. This assertion may be true of pseudo-sesamoids 
such as the osteomata of riders. It is entirely erroneous in the case of fabellae and cyamella which can 
be detected in embryos and the young shortly after birth by the presence of patches of hyaline cartilage 
as we have indicated: see our pp. 158 — 159 and Plates XVII and XVIII. 
