188 



METABOLIC HORMONES 



Table 20. Changes in fat content of the body of crabs {hemic rap sus 

 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. The differences in fat, due to sex, and 

 the losses after sinus gland removal are significant (from Neiland and 

 Scheer, 1953). 



NORMAL 



STARVED 

 23 DAYS 



STARVED WITH 



SINUS GLAND 



REMOVED 



Sex 

 Body weight, g 

 Fat index/g 



10-5 

 4-31 



F 



9-3 

 6-13 



M 

 9-5 

 4-76 



F 



7-4 

 6-4 



M 



10-3 

 2-82 



F 



7-4 

 3-79 



This, in conjunction with evidence on glycogen and chitin 

 content (Table 23), suggests that "the eyestalk principle of 

 crustaceans restrains . . . metabolism, but especially those processes 

 connected with preparation for a molt" (Neiland and Scheer, 

 1953). But this finding is, perhaps, somewhat sweeping, since the 

 authors appear only to have tested removal of the sinus glands, and 

 not to have compared this with removal of the whole eyestalk, nor 

 to have replaced either organ by injection of its extract. This is 

 important, since the sinus glands are usually only storage organs 

 for neurosecretory cells in the brain or the ganglionic-X-organ, 

 both of which were left intact in these experiments and might have 

 been expected to continue to supply some of the fat-preserving 

 hormone as well as of the moult-inhibiting hormone. It has already 

 been noted that the comparable hormone that restrains oxygen 

 consumption is more abundant in the whole eyestalk than in the 

 sinus glands alone (§ 5.112 and Fig. 5-7). 



Vertebrata. No hormones have been specifically associated with 

 fat storage invertebrates, apart from lack of thyroxine (§5.121) or of 

 thyrotrophin (§ 4.221). Relative inactivity of the thyroid seems to 

 be the main factor in allowing accumulation of the fat stores that 

 are necessary for hibernation in mammals (§5.112). 



It has been claimed that, in the brown trout, Salmo truttay most 



