216 INVERTEBRATE PHYSIOLOGY 



generally causes an increase in size beyond that of normal animals ( Smith, 

 1940; Abramowitz and Abramowitz, 1940). The increase is not merely 

 the consequence of increased frequency of molting, but results also from 

 a greater than normal increase in size following the first ecdysis (Scuda- 

 more, 1947; Bauchau, 1948b). Koch (1952) has raised the question 

 whether this increase in size, which he confirms, is true tissue growth, in 

 the sense of formation of new tissue. He observed in Eriocheir sinensis, 

 no difference in the nitrogen content of the exuvia or of the entire body 

 between normal and eyestalkless animals of the same size before molting. 

 After molting, however, the eyestalkless animals had much less nitrogen 

 than normal animals of the same size. Koch (1952) concluded, therefore, 

 that the increased size of eyestalkless animals is not the result of increased 

 synthesis of tissue protein. 



This conclusion is less firmly based than might appear. Drach (1939) 

 showed that, in normal crabs {Cancer paguriis, Maia squinado) , the syn- 

 thesis of new tissue does not begin until the C stage, some days after 

 ecdysis ; the volume increase, on the other hand, is complete within a few 

 hours. Renaud (1949) finds, for Cancer pagurus, that the total amount of 

 nitrogen in the digestive gland decreases after ecdysis until stage C, after 

 the carapace is completely calcified. Then the nitrogen increases, to a maxi- 

 mum in stage Di, the beginning of preparation for a new molt. Since Koch's 

 animals were analyzed soon after ecdysis, he may have missed this later 

 increase. Neiland and Scheer (1953) examined the effect of fasting and 

 removal of the sinus gland on the body composition of Hemigrapsus nudus 

 in the C stages of the intermolt cycle. Female crabs had a higher protein 

 nitrogen content, on a body-weight basis, than males. Fasting for 23 days 

 resulted in a decrease in the protein nitrogen content of females to the level 

 of the males, with no change in the latter. Removal of the sinus glands, 

 superimposed on fasting, resulted in a decrease in protein nitrogen in 

 both sexes. We concluded that removal of sinus glands induces an increased 

 tissue catabolism in fasted animals. It would be of interest to know the 

 effects of eyestalk removal from fed animals. Kincaid and Scheer (1952) 

 found evidence of an increased organic-matter content in fed crabs follow- 

 ing extirpation of the sinus glands. This work was done before we were 

 aware of the source of the eyestalk hormones in the X-organ, and requires 

 repetition with eyestalk removal. We concluded tentatively that the eye- 

 stalk principle involved directs tissue metabolism towards tissue growth 

 and away from processes concerned in preparation for ecdysis (Neiland 

 and Scheer, 1953). This conclusion requires further experimental test. 



Carbohydrate and Lipid Metabolism 

 In mammals and many insects, glycogen is the most readily available 



