178 



METABOLIC HORMONES 



5.112 Decrease in oxygen consumption 



Crustacea. One of the hormones from the ganglionic-X- 

 organ/sinus gland complex in the eyestalk of decapod crustaceans 

 decreases oxygen consumption. This may either be a direct action 

 or the hormone may inhibit the secretion, or action, of the brain 

 hormone which increases oxygen consumption (§ 5.111); but no 

 decision between these ahernatives is possible at present. 



The experimental evidence is not very satisfactory in the case of 

 individual species; but taken together the results are consistent 

 for all except Leander. 



6 :. — 



4 5 6 

 Time , days 



Fig. 5-5. Effect of eyestalk removal on the rate of oxygen con- 

 sumption in the crayfish, Cambarus immunis. N, average for six 

 normal crayfish; E, average for six crayfish from which both 

 eyestalks were removed at X (there is no explanation of the high 

 value for the previous 4 days); S, results for one crayfish from 

 which removal of one eyestalk at 2 days gave no effect, but removal 

 of the second at 4 days caused a marked increase in the one 

 subsequent measurement. It is claimed that the eyestalks supply a 

 RESPIRATION-INHIBITING HORMONE (from Scudamore, 1947). 



In Cambarus immunis there is no significant change in oxygen 

 consumption after the removal of only one eyestalk, and very little 

 after removing both sinus glands ; but removal of both eyestalks 

 allows the oxygen consumption to increase by about 60 per cent 

 (Scudamore, 1947). Extract of sinus glands alone, injected into 

 eyestalkless animals, is said to decrease oxygen consumption by 



