CATALEPSY IN PHASMIDAH. 



By PETER SCHMIDT. 



Privat Dozent of the Imperial University of St. Petersburg. 





In the following article I wish to give the results of 

 some observations and experiments upon cataleptical 

 phenomena in connection with an Indian insect — 

 Carausius morosus Br. v. W. — an Orthopteron of 

 the family of Phasmidae. The representatives of 

 this family are all tropical or subtropical insects of 

 green, grey or brown colour and protectively resemble 

 the stems of the plants on which they feed. The 

 habitat of Carausius morosus, which will breed 

 during any month of the year in my laboratory, so 

 far as I am aware, is North India and Afghanistan ; 

 but, five or six years ago it was imported into 

 Germany via Hamburg and thence came to St. 

 Petersburg, where it breeds now in almost all 

 zoological laboratories. The insects are so interest- 

 ing in many respects and their breeding is so easy 

 that it is really strange that these Indian emigrants 

 have up to the present been so little known in other 

 countries. Their biology was studied in detail by 

 an eminent German entomologist, Otto Meissncr,* 

 who published a valuable paper, but strangely did 

 not notice the most interesting feature about them, 

 viz., their catalepsy. 



These green stem-like creatures with red markings 

 on the femora of the forelegs show generally very 

 little movement. They may sit motionless during' 

 the whole day on the stems of plants or on the sides 

 of a glass jar (see Figure 357), and only occasionally 

 do they begin to move, and then they creep in a very 

 lazy way. They feed generally at night, and it is 

 very seldom that one can see a Carausius eating 

 leaves by day. 



The insects may be thought at first sight to be 

 sleeping or reposing, but closer observation and some 

 very simple experiments will produce the conviction 

 that we have to do here with a catalepsy exactly like 

 that artificially produced in higher animals. Indeed.it 

 has long been known that many vertebrates can be 

 hypnotised and made motionless by very simple 

 methods. If we lay a rabbit on his back on the 

 table and fix his head and his feet for a few seconds, 

 we shall make him cataleptic — he will lie motionless 

 for some minutes, and his muscles will be strained 

 as in a hypnotised human subject. The same thing 

 can be done with a crayfish — one can stand him 

 vertically on his head and the first pair of legs, and 

 he will keep completely motionless for many hours 

 as if bewitched. 



Now if we look more carefully at a Carausius in 

 his quiet state we shall see that his feet and whole 

 body are rigid, and his muscles are strained as in 

 catalepsy. Indeed, if we gently take hold of a leg 



with a pair of forceps, bend it, and put it in some 

 pose or other, we see that it keeps this pose for 

 a very long time, even if it is unnatural and uncom- 

 fortable. In the same way we can raise the head 

 and the prothorax of the animal and move asunder 

 the first pair of legs, so that Carausius takes approxi- 

 mately the position of a. Mantis (see Figure 359). In 

 such an artificial pose Carausius will stay for many 

 hours. 



When I had detected this interesting muscular 

 state in the quiet Carausius I tried some other 

 experiments, and after a number of trials it occurred 

 to me, for instance, to stand the insect on its head 

 (see Figure 358) and to give him a still more 

 amusing pose which I have called the " wrestling 

 bridge " (see Figure 360). In one of the experi- 

 ments a cataleptical Carausius remained on its head 

 for four and a half hours ! And he showed not the 

 slightest signs of fatigue. 



All these experiments sufficiently demonstrate that 

 the muscles of Carausius are really in a state which 

 is named by physiologists " flexibilitas cerea " 

 (i.e., wax flexibility). They are strained, but not 

 extremely as in the state of tetanus : they can be 

 stretched more and remain in a given position. 

 Expressly the same state of muscles is observed 

 in the cases of catalepsy or "hypnosis" in higher 

 animals and in man. 



How strong is this rigidity of muscles is seen 

 from the experiment shown in Figure 361. Here a 

 Carausius is posed between two books with the tips 

 of the forelegs on the one and with the end of the 

 abdomen on the other. A very considerable weight 

 for it, in the shape of some paper strips, has been 

 placed on its abdomen, so that it is bent like a bow, 

 and, notwithstanding, it will remain in the deepest 

 catalepsy for one or more hours in this strange pose ! 



It is known that catalepsy has two distinguishing 

 features : (1) a cataleptical subject does not feel 

 pain : one may cut and sting him, and he remains 

 in the same state of immobility ; (2) the cataleptical 

 tension of muscles does not cause fatigue. And, in 

 fact, a cataleptical Carausius is completely feeling- 

 less : with sharp scissors one can cutoff its antennae 

 and feet, and, one after the other, all the segments of 

 the abdomen ; its green blood flows from the wounds, 

 but it stays in the same pose completely motionless. 



In order to awake the insect from its hypnotic 

 sleep, a prolonged excitement of the nervous system is 

 needed. One can excite it mechanically, for instance, 

 by tweaking the end of its abdomen with forceps, or 

 by giving it electrical shocks with an induction coil. 



* Zeitsch. f. wissensch. Insektenbiologie, Bd. V, 1909, Heft 1-3. 



333 



