THE DIGESTIVE ENZYMES OF LEPIDOPTERA. 



343 



From the results of the experiments above mentioned, we 

 may conclude 



I. That in the stomach of silk-worms tryptic, diastatic and 

 lipatic enzymes are present, but that pepsin and pepsino- 

 gen are quite absent. 

 U. That the digestion of fat is effected by decomposition 

 into fatty acids, as in the case of Vertebrata. 

 The third experiment was made to ascertain the presence 

 of digestive enzymes in the intestine of insects. 3 grs. of the 

 intestines of silk-worms, which had been carefully separated 

 from the stomach and freed from their contents by washing 

 in water and then crushed in a mortar together with glass 

 powder, were digested with glycerin as in the former case. 

 After three days the mixture was further treated as above. One 

 of the portions was dissolved in about 20 c.c. of 0.4% HC1, and 

 the other in 20 c.c. of 0.3% solution of sodium carbonate. With 

 both of these solutions the experiment was performed as before, 

 and after six days the results observed were as follows : — 



Solutions. 



Materials 

 used. 



Temperature. 



Results. 



Acid solution of 

 the enzymes. 



fibrin. 



30 0 c. 



not dissolved. 







room- 

 temperature. 





13 



starch. 



30 0 c. 



not changed. 



»» 





room- 

 tempcrature. 





Alkaline solution of 

 the enzymes. 



fibrin. 



30 0 c. 



dissolved. 







room- 

 temperature. 



*) 





starch. 



30 0 C. 



not changed. 







room- 

 temperature. 







fat. 



30 0 C 



acid was not 

 set free. 



