NEOLAMARCKISM 403 
Ryder began in 1877 to publish a series of remark- 
ably suggestive essays on the ‘* mechanical genesis,”’ 
through strains, of the vertebrate limbs and teeth, 
including the causes of the reduction of digits. In 
discussing the origin of the great development of 
the incisor teeth of rodents, he suggested that ‘‘ the 
more severe strains to which they were subjected by 
enforced or intelligently assumed changes of habit, 
were the initiatory agents in causing them to assume 
their present forms, such forms as were best adapted 
to resist the greatest strains without breaking.’’ * 
He afterwards +t claimed that the articulations of 
the cartilaginous fin-rays of the trout (Salmo fonti- 
nalis) are due to the mechanical strains experienced 
by the rays in use as motors of the body of the fish 
in the water. 
In the line of inquiry opened up by Cope and by 
Ryder are the essays of Osborn { on the mechanical 
causes for the displacement of the elements of the 
feet in the mammals, and the phylogeny of the 
teeth. Also Professor W. B. Scott thus expresses 
the results of his studies:§ 
‘To sum up the results of our examination of cer- 
tain series of fossil mammals, one sees clearly that 
transformation, whether in the way of the addition 
of new parts or the reduction of those already pres- 
ent, acts just as 7f the direct action of the environ- 
* Proceedings Academy of Natural Science, Philadelphia (1877), 
p- 318. ; 
+ Proceedings of the American Philosophical Society (1889), p. 546. 
¢ Transactions American Philosophical Society, xvi. (18go), and 
later papers. 
§ American Journal of Morphology (1891), pp. 395, 398. 
