§ 5.211 CARBOHYDRATE METABOLISM 189 



fat is deposited in the gut wall around midsummer, when the 

 thyroid gland reaches the single peak of its activity, as estimated 

 by its accumulation of radioactive iodine (Swift, 1955). This seems 

 to be anomalous ; but it may be noted that fat is also deposited in 

 January, before the spring growth period. There may, therefore, 

 be no causal connection between fat deposition and thyroxine 

 secretion. 



5.2 Intermediary metabolism of carbohydrates 

 and proteins 

 The biochemistry of intermediary metabolism is complex, but 

 it need not be considered in detail here, since it is possible to 

 measure the end-products of anabolism or catabolism, rather than 

 the series of chemical transformations within these processes. 

 These measurements can then be related to hormone treatment. 

 Evidence is accumulating to show that in arthropods and in 

 vertebrates the metabolism of carbohydrates and of proteins is 

 often linked; but diiferent hormones may be concerned in con- 

 trolling the two types of metabolism, which will therefore be 

 considered separately. 



5.21 carbohydrate metabolism 

 Among the carbohydrates, sugars are most easily traced and 

 can be measured quantitatively in the blood, as they increase 

 in quantity after a meal, or after hormone treatment, and then 

 decrease as they pass into the tissues to be stored or assimilated. 

 Their distribution between the blood and the tissues is normally 

 maintained at a relatively stable level by a balance of hormones, 

 the diabetogenic type increasing the blood-sugars and the anti- 

 diabetogenic decreasing them. Evidence of both types have been 

 obtained in Arthropoda, as well as in Vertebrata (Table 21). 



5.211 Increase in blood-sugar by ''diabetogenic'' hormones 



Crustacea. The sinus gland is the main source of a diabeto- 

 genic hormone in both the crayfish, Astacus, and the blue crab, 

 Callinectes. This has been shown in carefully controlled compari- 

 sons (Table 22) between the effects of "stress" caused by asphyxia 

 in normal and in operated animals, from which either the whole 

 eyestalk or the sinus gland alone had been removed (Kleinholz 



