190 INVERTEBRATE PHYSIOLOGY 



is on the ovary itself or on some other organ which normally secretes an 

 accelerating" or gonadotropic hormone. Experimental procedures to an- 

 swer this question faced technical difficulties ; but, in the light of some re- 

 ports of neurosecretory structures associated with the cerebral ganglia, 

 Panouse undertook implantations of such tissues into a small number of 

 animals. No significant effect on ovarian growth was detectable, but 

 Panouse himself recognized that the small number of animals (26) in- 

 volved and the possibility of insufficient implantations make repetition of 

 this experiment desirable. 



Panouse's results were confirmed on a number of other crustaceans by 

 Brown and Jones (1947, 1948) and by Carlisle (1953b). A study of the 

 reproductive cycle in the female crayfish by Stephens (1952) postulates 

 the participation of a number of hormones, two from the sinus gland and 

 two from the cerebral ganglia, but these proposals are still speculative and 

 require experimental verification. 



On the other hand, results reported by Arvy, Echalier, and Gabe ( 1954) 

 present more adequate evidence for an additional source of an endocrine 

 substance which is gonadotropic in function. These authors find that bi- 

 lateral removal of the Y-organ (described above in the section on molting) 

 in sexually immature Carcinides results in ovaries in which oogonia and 

 mitoses are rare, follicle cells and vitellogenesis of the oocytes are reduced, 

 and cytolysis of oocytes has occurred. Comparable anomalies appear in 

 similarly operated males. Removal of the Y-organ in sexually mature males 

 and females has no observable effect, such operated animals not being 

 different from normal controls given blank operations. At this stage the 

 authors are unable to decide whether the effect on the gonads is a general 

 metabolic one, because of the arrest of the molting rhythm, or whether it 

 is a specific gonadotropic effect limited to gametogenesis. The Y-organ 

 may be a structure which is physiologically in balance with the sinus gland 

 in regulating ovarian growth, a relationship that would be worth closer 

 examination. 



Other Activities and Other Phyla 



In very few animal phyla other than the arthropods have endocrine pro- 

 cesses been demonstrated in much detail. For the most part, studies among 

 the other phyla consist of scattered observations, which have been sum- 

 marized in some of the early reviews, particularly that of Hanstrom 

 ( 1939). On the other hand, there have been a number of studies of neuro- 

 humoral activity among invertebrates, many of which are reviewed in this 

 symposium by Welsh. Recent studies of the distribution of catechol amines 

 in invertebrates (Ostlund, 1954), reviews of the pharmacology of indo- 

 lealkylamines, particularly of 5-hydroxytryptamine (Erspamer, 1954), 



