248 



METABOLIC HORMONES 



moulting rate at the same time. Most of the evidence is indirect 

 and derived from observations on sinus gland and eyestalk removal ; 

 but in Camharus (Scudamore, 1947) injections of sinus gland 

 extract result in a decrease in the level of blood calcium, after it has 

 been raised by eyestalk removal. The level does not return to 

 normal ; but different dosage levels have not been tested. 



Removing the sinus gland only, as compared with removing the 

 whole eyestalk in Astacus, has the results on the level of blood 

 calcium shown in Table 30. 



Table 30. Changes in the calcium content of the blood of the 



crayfish {astacus)^ following removal of either the sinus glands 



or the whole eyestalks 



Values for Ca in mg % (from figures given by Havel and Kleinholz, 



1951). 



This shows that some structure in the eyestalk, other than the 

 sinus gland, can produce the calcium-decreasing hormone. It is 

 presumably the ganglionic-X-organ, which is the usual source of 

 the hormone stored in the sinus gland, but it has not been located 

 for certain (Havel and Kleinholz, 1951). 



Amphibia. As mentioned above, a hormone from the neuro- 

 hypophysis is said to decrease the serum calcium in Xenopiis^ when 



