ENDOCRINOLOGY OF CRUSTACEANS 189 



of hormones from the gonad. These authors were able to perform surgical 

 castration upon male and female isopods, and found no consequent modifi- 

 cation of the permanent sex characters. Oostegites, which constitute a 

 brood pouch for developing young, formed in more than 90% of castrated 

 females and are thus independent of the gonad. Since earlier investigators 

 had reported that radiation castration was followed by failure of the 

 oostegites to develop (hence the argument for a hormone from the ovary 

 to maintain the oostegites), it seems unjustifiable from the results of 

 Takewaki and Nakamura to explain such changes in terms of destruction 

 of the gonad. 



Reinhard (1950) proposed that differentiation of the inner rami of the 

 pleopods of Callinectes, similarly associated with care of the developing 

 young, was under the influence of an ovarian hormone. It may be unwise 

 to extend the conclusions from one order of crustaceans, the isopods, to 

 another, the decapods ; but, in the absence of any more positive evidence 

 for ovarian hormones, the results of the Japanese workers remain without 

 substantial challenge. 



The cement glands in the female crayfish are a secondary sex character 

 for which the possibility of nonovarian endocrine control factors have been 

 indicated by Stephens ( 1953). This author reports a factor in the eyestalks 

 which inhibits development of the cement glands in the mature female ; a 

 possible role of neurosecretion from the central nervous system in regu- 

 lating these structures is suggested by implantation experiments, but 

 Stephens believes further experimental verification is desirable. 



Studies reporting endocrine effects upon the gonads themselves seem 

 to be based on more substantial evidence. Panouse ( 1946) was the first to 

 report a marked effect of eyestalk removal in Leander serratus on the 

 ovaries. He found that by 45 days after eyestalk removal the wet weight 

 of the ovary was 13 times that of unoperated control animals, and the dry 

 weight more than 30 times that of controls. These results occurred in ex- 

 periments execvited well before the normal breeding season ; the egg lay- 

 ing which follows such ablation experiments appeared normal. To charac- 

 terize these results more adequately as a possible endocrine effect, surgical 

 removal of the sinus glands was done on one group of animals and was 

 found to give similar results, but not as marked as those obtained with eye- 

 stalk removal, in explanation of which Panouse suggested the possibility 

 of incomplete sinus-gland removal. Reciprocal experiments involving 

 weekly implantations of 2 sinus glands into the abdomens of animals with- 

 out eyestalks not only prevented the rapid growth of the ovary, but actually 

 depressed ovarian weight below that of normal unoperated animals. The 

 evidence from these experiments suggests an inhibitory hormone from 

 the sinus gland, but the question arises as to whether the inhibitory effect 



