Holmes, Death-feigning in Ranatra. 203 



insects that feign death. In certain spiders that feign death the 

 condition is described by Robertson^ as one of " extreme tetanus." 

 In most cases the appendages are drawn up close to the body. 

 In some amphipods and isopods the body is strongly flexed and 

 the legs drawn up into a compact form — a condition that can be 

 maintained only through the exercise of a constant muscular 

 strain. An apparently similar state occurs in the rigid form in 

 which the asp and certain other serpents may be thrown by the 

 proper manipulation. And it is not improbable that the cata- 

 leptic stage that sometimes occurs in hypnotized human beings 

 may fall within the same general category of physiological phe- 

 nomena. 



One striking peculiarity of the death feint in Ranatra is the 

 apparent insensibility to pain which is shown. One may perform 

 the most severe mutilations upon an individual that is feigning 

 death without evoking the least manifestation of feeling. This is 

 well illustrated by the following experiment: In a Ranatra that 

 was caused to feign death the four hinder legs were cut 'off one 

 by one. Not a wince. Both anterior legs were then cut off, and 

 after a slight jerk the insect was as immobile as before. The tip 

 of the abdomen was cut off. No movement. Then the abdomen 

 was cut off next to the thorax. Still no response. Then 

 the body was cut in two across the thorax leaving a short 

 middle piece with the stubs of two pairs of legs and the anterior 

 end of the insect with the stubs of the anterior legs. No move- 

 ment in either piece. In eight minutes the stubs of the anterior 

 legs began to move in a lively manner. The head piece was then 

 picked up and stroked when it was again thrown into a rigid 

 condition. 



DURATION OF SUCCESSIVE DEATH FEINTS. 



In experimenting upon the duration of successive death feints 

 in the beetle Scarites, Fabre^ found that there was a gradual 

 increase in the length of the feint the oftener the insect was 

 compelled to repeat the performance. In the experiment cited the 



'Robertson, T. B. On the Sham Death Reflex in Spiders. Jour. Physiol., Vol. 31, p. 410. 

 1904. 



'Souvenirs Entomologiques. yme. Ser., p. 14,, 



