The Instinct of Feigning Death 215 



muscles. Similar phenomena are observed in the 

 death feigning of many forms, some of the insects, 

 as we have seen, showing a lack of responsiveness 

 that is truly remarkable. 



The independent development of death feigning 

 along many different lines of descent makes it prob- 

 able that we must look for the origin of this curious 

 instinct in some fundamental and widespread mode 

 of behavior. In a paper on the death feigning of 

 terrestrial amphipods the writer has suggested that 

 the death-feigning instinct in these forms had its 

 origin in an accentuation of the thigmotactic re- 

 sponse which is such a prevalent trait of behavior 

 among the amphipods in general. It was found pos- 

 sible to establish a series of stages between the typ- 

 ical death feint of the large terrestrial amphipod 

 Talorchestia and the ordinary thigmotactic reactions 

 of the aquatic relatives of this species. In Orchestia 

 palustris, a species not so exclusively terrestrial as 

 the preceding, the body during the death feint is less 

 closely curled up, the appendages are not so closely 

 drawn up to the body, and the feint is not so per- 

 sistent. In the small Orchestia agilis, which lives 

 usually near the water line, the death feint is shown 

 in a somewhat less decided way, while among the 

 aquatic members of the Orchestiidae the same trait 

 is manifested by a tendency to curl up and lie quiet 

 when in contact with rocks or seaweed. To one who 

 has studied and compared the attitudes and behavior 

 of this series of forms there can be little doubt that 

 the typical death feint of the most terrestrial of the 



