was so striking that it could not be observed at all by whatever method used 

 (Fig. Ill — 15). 



Pupation did not cause a change in the activity of the esterases which 

 hydrolize the acetic acid esters (Fig. II — 12). 



It could be shown that the other esterases were more active during pupation 

 than during the moulting periods. They were especially active towards the 

 esters of stearic and oleic acid. The deposits of the reaction products were 

 visible chiefly in the cells which were being autolized. In the newly formed 

 epithelium no esterase activity could be found by cytochemical methods (Fig. II 

 — 13 and 14). The same phenomenon was observed in case of the phosphatases. 

 Both the alkaline and the acid phosphatase were very active only in the auto- 

 lyzing larval epithelium. The new epithelium seemed to be of a very low 

 enzymatic activity (Figs. Ill — 16 and 17). 



In adults — which never feed — the alimentary tract showed a very low 

 activity of the phosphatases as well as of the esterases. If compared with the 

 strong reaction of some parts of Malpighian tubes hardly any reaction of 

 esterase (Fig. Ill — 18) or alkaline phosphatase (Fig. Ill — 19) activity 

 could be found in the intestine of imago. 



Some observation made on the alimentary canal of adult Achroa grisella, 

 which is related to Galleria mellonella L. and which similarly does not feed, 



é 



Table I 



E xplantations : 



+ + + + a very' strong reaction, + + + strong reaction, -f + moderate reaction, + weak reac- 

 tion, о no positive reaction observed. 



176 



