MOULTING HABITS OF SPIDERS. 115 



hearing, and touch, of movement, and even of respiration for a short time. 

 4. To the moult are subject most of the ectodermic and part of the meso- 

 dermic products. 5. The blood corpuscles, which with spiders are formed at 

 the expense of the endoderm, are subject at each moult to periodic modifica- 

 tions, the final result of which is their proliferation. The number of red 

 blood corpuscles increases from being three or four per cent, to become ten 

 per cent, of the whole. 6. Cotemporaneously with the above named periodic 

 processes of moulting are wrought certain constant processes of interior 

 and exterior modifications, which are chiefly accomplished at the moulting 

 period with which they are found in more or less direct connection. 7. 

 The modifications to which spiders are subject during their post embryonic 

 development are by no means limited to shape and to the final develop- 

 ment of the genital organs. 8. With the moulting of spiders are connected 

 certain special faculties, which are proper to the animal only during the 

 moulting period, such, for example, is the faculty of renewing lost organs. 

 Thus, if a spider's foot be lost during that period of life within which it 

 is subject to moulting changes, it will be renewed after every moult ; but if 

 a limb be lost after the same period it will never be restored. 9. In con- 

 nection with one or another of its various moults, the spider is found in 

 possession of certain provisional organs, some of which soon disappear, 

 others only with sexual maturity. 10. Finally, it may be stated that the 

 moulting processes of spiders are almost exactly similar to those of the 

 larvjE of insects which undergo an incomplete metamorphosis, as the 

 Orthoptera, Pseudoneuroptera, and Hemiptera. 



