272 Annals Entomological Society of America [Vol. IX, 



remaining accompanying manifestations, as, for instance, the 

 response to external stimuli, seem to correspond to those well- 

 known and familiar forerunners of sleep, the specific rigidity 

 among insects of the (cataleptic) muscular strain is just the 

 opposite of our usual conceptions of sleep. To be sure, we 

 recognize certain sleep-like manifestations, which at present are 

 causing much discussion, resulting from hypnotism, often 

 bringing about most surprising results, and, just as among 

 bees, showing the strangest departures from normal rest posi- 

 tions. We also speak of an hypnotic sleep, a rigidity brought 

 on by hypnotism. We do not understand as yet the physiolog- 

 ical processes of these cataleptic conditions observed among 

 vertebrates. Do similar physiological processes exist in the 

 sleep of insects, in the clinging colonies of bees and wasps, as 

 take place in the hypnotic sleep of vertebrates? It is a well 

 known fact that not only man is susceptible to this form of 

 sleep, but also many, psychologically poorly developed, verte- 

 brates, as, for example, the hen. Is perhaps this hypnotic-like 

 sleep of insects the forerunner of our present fully developed 

 form of sleep, in which, because of the high development of the 

 psychological, i. e., the nervous system, the assimilating and 

 reviving processes are more complete and radically more 

 intensive? Such cataleptic or hypnotic sleep in the higher 

 vertebrates could be regarded as an atavic form of sleep. This 

 view would receive considerable support if we were to assume 

 that such a sleep was the rule among cold blooded animals of 

 the present day and particularly among the giant lizards and 

 amphibians of prehistoric ages. The fact that this so-called 

 "hypnotic" sleep is of a decidedly passive nature and only 

 brought about through the influence of an external organism 

 need be regarded of only secondary importance for our compar- 

 ison, in which the cataleptic manifestations accompanying sleep 

 are the vital considerations; it can readily be assumed that 

 among insects instead of a person an object, i. e., any external 

 factor, to a certain extent could act as hypnotizer (for example, 

 light or its absence.) 



Although we may compare the manifestations of sleep among 

 insects with a known form of sleep, we have not advanced very 

 much further in knowing its nature, particularly so, since the 

 physiological nature of hypnotic sleep is, I believe, still unknown. 

 It would be carrying me too far were I to consider — even 



