CRUSTACEAN METABOLISM 219 



and fucose ; only the glucose of this polysaccharide was labeled, and no 

 label was found in the chitin. 



Evidence that carbohydrate metabolism is under control of an endocrine 

 factor in the eyestalks was obtained first by Abramowitz, Hisaw, and 

 Papandrea (1944). They found that eyestalk extract, or extracts of the 

 sinus glands, of Uca pugilator or of Callinectes sapid us had the eflfect of 

 increasing the reducing value of the blood in these crabs. Kleinholz and 

 Little (1949) performed similar experiments with Libinia eumrginata 

 and obtained similar results. Moreover, they were able to provide evidence 

 that the increased reducing value is primarily an increase in the fermentable 

 fraction. Neither Abramowitz and coworkers (1944) nor Kleinholz and 

 Little (1949) observed any decrease in blood reducing value following 

 eyestalk removal ; no determinations of fermentable reducing substances 

 were made on eyestalkless animals. Scheer and Scheer (1951) removed 

 eyestalks from Panulirus japonicus and P. penicillatus, and found a sig- 

 nificant decrease in blood reducing values following the operation. The 

 values for eyestalkless animals were approximately 53% of those for un- 

 operated controls. Injections of eyestalk extracts caused a marked in- 

 crease in reducing value in normal or eyestalkless specimens, and the 

 increase was entirely in the fermentable fraction. Indeed, in two of three 

 experiments, the increase in the fermfentable fraction was considerably 

 greater than the increase in total reducing substances. 



Kleinholz and Little ( 1949) and Kleinholz, Havel, and Reichart ( 1950) 

 repeated earlier observations concerning the effects of anoxia, anaesthesia, 

 and adrenaline on the blood reducing values in Libinia emarginata, AstacHS 

 trowbridgi, and Callinectes sapidus. They found that the hyperglycemia 

 following asphyxia is mediated by the sinus gland in all three species, since 

 the hyperglycemia failed to occur in animals from which this gland had 

 been removed. In A. trozvbridgi the hyperglycemia following chloroform 

 anaesthesia or adrenaline injections likewise depends on the sinus gland, 

 but in C. sapidus adrenaline produces hyperglycemia even in eyestalkless 

 animals. Kleinholz et al. (1950) concluded that the diabetogenic hormone 

 of the eyestalk is responsible for most of the hyperglycemic effects ; the 

 action of adrenaline in C. sapidus may result from activation of a source 

 of hormone outside the eyestalks, or from a direct action of adrenaline 

 on carbohydrate metabolism. 



Scheer and Scheer (1951) attempted to learn something of the mech- 

 anism of action of the diabetogenic factor. Glucose tolerance studies showed 

 that the rate of removal of injected glucose from the blood is much greater 

 in eyestalkless than in normal lobsters. In view of the evidence already 

 discussed, that the principal function of glucose is in the formation of chitin, 

 we concluded that the diabetogenic hormone acts to restrain the conversion 



