100 COMPARATIVE PHYSIOLOGY 



The structure of the alimentary canal in Arthropods has 

 prompted several investigations into the localisation of absorp- 

 tion in these animals. The greater part of the tract is lined 

 with chitin. In the case of the cockroach Sanford's observa- 

 tions conclusively prove that absorption can take place in the 

 fore- gut of some insects. On the other hand, the work of 

 MurHn, Cuenot, Jordan, Yonge, and others clearly shows that 

 in Crustacea absorption is confined to the mid-gut and the 

 tubules of the digestive gland. Direct experiment shows that 

 the fore and hind gut behave as semipermeable membranes to 

 glucose and salts, which, however, penetrate the wall of the 

 mid-gut. 



References 



Bacot and Harden (1922). The Vitamin Requirements of Drosophila. 



Biochem. Journ. 16. 

 BoDANSKY AND RosE (1922). Comparative Studies on Digestion I-II. 



Am. Journ. Physiol. 

 Coward and Drummond (1922). On the Significance of Vitamin A in the 



Nutrition of Fish. Biochem. Journ, 16. 



Dakin and Dakin (1925). The Oxygen Requirements of Certain Aquatic 

 Animals and its bearing on the Food Supply. Brit. Journ. Exp. Biol. 2. 



Hunt (1925). The Food of the Bottom Fauna, etc. Journ. Marine Biol. 



Ass. 13. 

 Miller ( i 9 i o) . On the Rhythmical Contractibility of the Anal Musculature 



of the Crayfish and Lobster. Journ. Physiol. 40. 



Orton(i9I2). The Mode of Feeding in Crepidula. Journ. Marine. Biol. 



Ass. 9. 

 Sanford (191 8). Experiments on the Physiology of Digestion in the 



Blattidas. Journ. Exp. Zool. 25. 



Ten Cate (1923-24). Contributions a la physiologie du coeur de Tanodonte. 

 Arch. Neerland. Physiol. 8. 



Contributions a la physiologie comparee du canal stomaco-intestinal. 

 I-ni. Ibid. 9. 



Yonge (1923-24). Studies on the Comparative Physiology of Digestion. 

 I-II. Brit. Journ. Exp. Biol. i. 



