328 STEFAN KOPEC. 



sidered, but three days later. From Table II. it is evident that 

 here the percentages are quite different : almost all caterpillars 

 undergo pupation. The specimens which did not succeed in be- 

 coming pupae live no longer than the normal larvse and their death 

 evidently results from the injuries of the operation. In this case 

 the metamorphosis of the caterpillars operated upon does not 

 undergo any retardation. 



The above-mentioned experiments of Conte and Vaney ('n) 

 must have been performed on such older specimens. In my pre- 

 vious paper (Kopec", '12), in which, like the authors mentioned, I 

 stated that the nervous system is unimportant up to the time of 

 pupation, I relied only on full-grown specimens; in view of my 

 present data, the former opinion can no longer be upheld. It 

 follows from further operations that none of the other nervous 

 ganglia (in contrast to the brain) has any influence on the time of 

 pupation. 



The dependence of the metamorphosis of the insect on its brain, 

 already discussed, and its independence of the other ganglia, may 

 be observed in one and the same specimen by means of a special 

 method of cutting the caterpillars. Having made ligatures with 

 strong silk round the body of the caterpillar into places chosen ad 

 libitum, and having made a section between the ligatures, we may 

 obtain two separate parts from one caterpillar, both of which are 

 able to live. For instance, in one series of experiments the cater- 

 pillars were operated upon 7 days after their last moult, and it 

 was found that the parts composed of the head and a few segments 

 of the larval body attained the stage of pupation in from 7 to 9 

 days after the time of operation. Larger or smaller parts of the 

 hind segments of the body devoid of the brain did not succumb till 

 35 days after the operation, but at death they exhibited no traces 

 of histolytical processes. When caterpillars a few days older were 

 operated upon both fragments underwent pupation at the normal 

 time. 



B. THE NATURE OF THE INFLUENCE EXERTED BY THE BRAIN ON 

 THE COURSE OF METAMORPHOSIS. 



If the influence exerted by the brain on the course of meta- 

 morphosis were by means of nerves, it might be supposed that the 



