INHERITANCE IN THE "WALKING-STICK.' 



245 



remembered that the curves fit the ventro-lateral contour of the 

 head to a remarkable degree. 



When the first pair of legs are so stretched forward the insect's 

 antennae are brought together. The legs have an irregular 

 groove extending along the approximated surfaces and when 

 complete approximation takes place a rather imperfect tube is 

 formed enclosing the antennas. This is a case analogous to the 

 above and it is difficult to imagine how chance variations could 



FIG. 3. Aplopus in the act of hatching from the egg. The body and head come 

 out first, then the antennas and finally the legs free themselves from the shell. The 

 parts of the first legs between xx are curved to fit the head when they are straight- 

 ened forward although they have never touched the head up to this time. 



bring about such mechanical harmonies between organs only 

 associated through an habitual attitude assumed by the animal 

 when at rest. Yet it must not be forgotten that many other 

 equally as nice morphological arrangements exist which have no 

 habit or action connected with them. Indeed a crucial case of 

 use inheritance is almost impossible to imagine from purely 

 descriptive work. I would not be understood as advocating any 

 principle of inheritance but merely bring forward the present case 

 as being of interest in itself. 



CORNELL MEDICAL SCHOOL, NEW YORK CITY, 

 February 6, 1909. 



