265 



others must be attribiitt'd for a great part to thcir not having 

 exainined the younger instars. 



I should have liked to study the living aniinals only, but this 

 proved to be too difticult. ïherefori; the animals wei'e nearly 

 always preserved in alcohol of OO'Y^. As I have already said, this 

 causes the colour to disappear for the greater part. Nearly the 

 whole material has been cultivated in the Zoological Laboratory 

 in the University of Groningen. Mr. E. Theyssen, the attendant 

 of the Laboratory, was charged with the care of the living animals 

 and with preserving them ; and here I wish to thank him for the 

 troiible he has taken. Before the investigation the preserved cater- 

 pillars were soaked in glycerine-gelatine. A certain quantity of 

 this substance in a solid state was placed on the object-glass, on 

 which the Caterpillar also lay, moistened by alcohol. The glycerine- 

 gelatine on the object-glass was somewhat heated till it became 

 entirely liquid, when it mixed with the alcohol. Thus I obtained 

 preparations which did not shrivel up and which on the whole 

 kept very well. Yery thick caterpillars had to be examined in 

 a dry state or lying in a watch-glass with alcohol, sometimes after 

 the hairs had been eut very short. 



Besides this material I could dispose of the magnificent collec- 

 tion of Dr. F. W. O. Kallenbach at Apeldoorn. This very rich 

 collection has been presented by the collector to the Zoological 

 Laboratory in the University of Groningen. Besides the numerous 

 imagines it contains the mounted and dryed caterpillars of most 

 of the species and of many even more or less complete series 

 of the stages of development. The specimens which I have used 

 are indicated by CoU. Kali. Many entomological plates I have 

 looked through, and though the objections already mentioned could 

 not be discarded, the figures sometimes gave valuable indicatiöns 

 as to the direction in which the further investigation had to be 

 made. The works indicated with an asterisk give the most correct 

 figures and descriptions. As a proof of the unreliability of the 

 figures in scientific entomological works, I draw attention to the 

 figure Taf. III, fig. 38 in Weismann's before mentioned study 



