Endocrine Mechanisms 759 



a diabetogenic action of the pituitary, has been confirmed in lower verte- 

 brates. Removal of the whole pituitary or of only the anterior lobe in toads 

 ameliorates pancreatic diabetes. ^^^ The anterior lobe of the dogfish, Muste- 

 lus, possesses a similar principle.^ Hypoglycemia follows hypophysectomy 

 in this fish, an effect reported as following removal of only the anterior lobe. 

 Furthermore, removal of the anterior lobe decreases the severity of diabetes 

 experimentally induced in these fishes by removal of the pancreas. 



Experiments involving thyroid administration to fishes appear to indicate 

 that this hormone has no influence on O2 consumption in the guppies and 

 goldfish.*^*'- ^^^ Treatment with thiourea does not significantly alter O2 con- 

 sumption in Fundiiliis.'^^'-^ Injection of extracts of thyroid glands of Bermuda 

 parrot fish increased O2 consumption in white grunts, but only when the 

 latter fish weighed more than about 15 grams.^*'^ As in most fish, adminis- 

 tration of thyroid to Rana fifiens tadpoles prior to changes of metamor- 

 phosis resulted in no alteration in O2 consumption.^^ In adult Rana fifiens, 

 on the other hand, administration of thyroid increased O2 consumption sub- 

 stantially,^*''^ and if the animals were kept at temperatures higher than about 

 13° C. caused reduction in body weight. Among the reptiles and birds the 

 effect of thyroid administration on the basal metabolic rate appears quite 

 similar to that observed in mammals. Pigeons show a marked reduction in 

 basal heat production after complete thyroidectomy.^^" 



Young Python, during long-continued thyroid feeding, show greatly in- 

 creased excitability and weight reduction.^***' 



A further suggestion that endocrine control of intermediary metabolism 

 of fishes differs markedly from that in higher vertebrates is seen in the com- 

 parative effects of adrenalin on O2 consumption. Whereas administration 

 of adrenalin to normal mammals produces a considerable elevation, in the 

 fish Girella there is only a reduction, and this latter occurs only in response 

 to doses which are huge in comparison with effective doses in the mam- 

 mal.i'^6 



Invertebrates. There is no conclusive evidence that any of the hormones 

 of the vertebrates which have a definite influence on intermediary metabol- 

 ism within that group have any comparable actions in any invertebrate. It 

 seems well established, however, that among the arthropods, at least, hor- 

 mones do have an influence on general metabolism. Removal of the eyestalks 

 or of the sinus glands of these stalks of Camharus is promptly followed by an 

 elevation in basal metabolism, as evidenced by the observed increase in O2 

 consumption.^"*^ This can be reduced by injection of aqueous extracts of 

 the glands. Injection of extracts of eyestalks of Uca, the fiddler crab, into 

 Callinectes, the blue crab, results in a rapid rise in the blood sugar from 

 about 20 mg./lOO cc. to more than 80.-^ The maximum is reached in one 

 hour, and then there is a slow decline to normal. This latter action has been 

 attributed to the presence of a diabetogenic factor in the crustacean sinus 

 gland, and recent work has confirmed this conclusion for the spider crab 

 hihinia.^^'^ 



In the grasshopper, Melanoflus, the corpora allata appear to be essential 

 for normal fat metabolism in the female.^-^ The female in adult develop- 

 ment first shows a rapid rise in fatty-acid content and much fat storage in 

 the fat bodies. This period, also one of the early growth of oocytes in the 



