Investigations on the Digestive Enzymes of 

 Some Lepidoptera. 



BY 



S. Sawamura. 



The digestive organs of Vertebrata consist of the mouth, 

 stomach, and intestines. The saliva secreted in the mouth is 

 alkaline ; the gastric juice of the stomach, acid ; and the 

 pancreatic juice and bile secreted into the intestines, alkaline : 

 thus the reaction of the fluids in the alimentary canal from 

 mouth to rectum changes several times. But, as to Lepidoptera, 

 the reaction of the fluids is alkaline throughout the digestive 

 canal. Hence, there arises the question as to whether the 

 digestive enzymes of these animals are different from those of the 

 Vertebrata. 



As the silk-worm (Bombyx viori.) is the most useful insect 

 in this country, it has been much studied, and thus the mor- 

 phological character of Lepidoptera has become comparatively 

 well known ; but our knowledge of its digestive process is 

 still very scanty. O. Kellner ' made an investigation on the 

 digestibility of mulberry-leaves by silk-worms, and found that 

 they could digest albumin, fat and carbohydrates except 

 cellulose ; but his investigation did not extend to the process 

 of digestion itself. 



Not only with Lepidoptera, but also in the whole division 

 of Insecta, the digestive enzymes are very imperfectly under- 

 stood. The first investigators on this subject were Plateau and 

 Jousset." 2 The former concluded, from his investigations, that 

 the fluid in the fore-intestine (now commonly called the 

 fore-stomach) being neutral or alkaline, contained diastatic 

 enzyme, which the investigator thought to be secreted by 



1 Landw. Versuchsstationen. 1886. 



7 Jahrcsbericht iiber die Fortschritte dec Tierchemie. 1877. 



