200 



METABOLIC HORMONES 



of nitrogen in the crab, Hemigrapsus. Sinus gland removal also 

 leads eventually to moulting, because of the absence of the moult- 

 inhibiting hormone (Part II, § 3); but it is probable that the time 

 required for moulting w^ould be more than the 23 days of the 

 experiments summarized in Table 23 (Neiland and Scheer, 1953). 



Table 23. Changes in body composition of crabs (hemigrapsus 

 nudus) following starvation and sinus gland removal 



All values are given on a wet weight basis and are means of measure- 

 ments on two to four individuals (cf. Table 20). The changes in protein 

 content, following the operation, are significant and are shown in italics 

 (from Neiland and Scheer, 1953). 



NORMAL 



STARVED 

 23 DAYS 



STARVED WITH 



SINUS GLAND 



REMOVED 



The results may be taken to represent the intermoult situation. 

 The effects of fasting and the technique of sinus gland removal 

 in Hemigrapsus have been referred to already in relation to reduc- 

 tion of fat (§ 5.112). Their effect upon glycogen "which might be 

 regarded as the most logical source of glucose and of chitin", is not 

 appreciable, and supports the suggestion that the crabs w^re not 

 near moulting, v^^hen new chitin is formed. There appears to be a 

 certain weight loss, which is reasonable in starved animals ; but it 

 would not occur in those from which removal of eyestalks was 

 inducing moulting, as this is accompanied by increased water 

 uptake (§ 5.321). It is claimed that in these conditions the reduction 

 in total nitrogen is significant, and represents the effect of removing 

 an eyestalk hormone that normally restrains protein catabolism. 



