THE OPINIONS OF NEO-LAMARCKIANS. 525 



circumambient medium, would confirm the inequality, 

 and put individuals of its kind at a disadvantage when 

 they varied towards the original shape." 



This is an excellent statement of kinetogenesis in 

 concentrated form. 



Prof. A. S. Packard in an important essay "On 

 the Evolution of the Bristles, Spines, and Tubercles 

 of Certain Caterpillars," etc., remarks as follows \ x 

 "The Lamarckian factors (1) of change (both direct 

 and indirect) in the milieu, (2) need, (3) habit, and the 

 now generally adopted principle that a change of func- 

 tion induces change in organs, and in some or many 

 cases actually induces the hypertrophy and specialisa- 

 tion of what otherwise would be indifferent parts or 

 organs. These factors are all important in the evolu- 

 tion in the colors, ornaments, and outgrowths from 

 the cuticle of caterpillars. . . . 



"So far as I am aware no one has suggested why 

 these horns and high tubercles and often pencils of 

 hairs are restricted to these particular segments. As 

 a partial explanation of the reason, it may be stated 

 that the presence of these high tubercles, etc., is cor- 

 related with the absence of abdominal legs on the seg- 

 ments bearing the former. It will also be noticed that 

 in walking the apodous segments of the caterpillar are 

 more elevated and prominent than those to which the 

 legs are appended. They tend to bend or hump up, 

 particularly the first and the eighth abdominal, the 

 ninth segment being reduced to a minimum, and the 

 tenth simply represented by the suranal and paranal 

 plates, together with the last pair of legs. 



"As is well known, the loopers or geometrid worms, 

 while walking elevate or bend up the part of the body 



1 Proceedings of the Boston Society of Natural History, 1890, p. 493, 510-513- 



