Digestion in Blattid/E. 



193 



culture. This is quite remarkable, because the living agent of 

 cyanolophia is not surpassed in virulence by any other virus. 



The next series of experiments will deal with the attenuation 

 of the living agents of cyanolophia in brain and liver tissue cul- 

 tures and with the importance of these and the white bone marrow 

 tissue cultures for active immunization. 



109 (1173) 



Experiments on the physiology of digestion in Blattidse. 

 By ELDON W. Sanford. (By invitation.) 

 [From Osborn Zoological Laboratory, Yale University.] 



The question as to whether fat is digested and absorbed in the 

 crop of the cockroach was answered in the affirmative by Professor 

 Petrunkevitch in 1898, but in the negative by more recent authors. 

 My investigations, which were done under the direction of Pro- 

 fessor Petrunkevitch, show that fat is split to soluble products 

 and absorbed in large amount in the crop, the process being ob- 

 servable as gradually more and more in the crop's epithelial cells 

 at successive intervals up to forty-eight hours, and gradually less 

 afterward. Some cells absorb so much that they appear solid 

 black when stained with osmic acid. Ligation of the crop from 

 the stomach does not hinder or modify the process. Fatty acids 

 are absorbed like fats. 



At certain intervals after fat feeding much fat is found in the 

 tracheal tubes, sometimes filling them, sometimes in a thin layer 

 on their walls, sometimes only on the supporting spirals, and 

 sometimes mingled with chyme. This chyme resembles that 

 normally present in the crop lumen; it is regularly present in some 

 of the tracheae, and in it leucocytes are often found. The chyme 

 is evidently a normal content. The fat enters the tubes through 

 the tracheal end cells, after being absorbed by them from the 

 lumen of the crop. 



