ENDOCRINOLOGY OF CRUSTACEANS 191 



and studies of activity of crustacean pericardial organs on the crustacean 

 heart (Alexandrowicz and Cadisle, 1953) all give indications of endocrine 

 characteristics and the possibility of function as a neurohumor in normal 

 physiological processes. Further studies will be able to distinguish between 

 physiological and pharmacological effects of these substances. 



Laviolette (1950) has verified reports by earlier investigators of hor- 

 monal influence of the gonad on secondary sexual structures of the genital 

 tract in gastropod mollusks. Fragments of the hermaphroditic gonad of 

 Mesarion, from which all spermatozoa were absent and containing only 

 fully grown oocytes, were implanted into young Arion or into individuals 

 with infantile genital tracts. The hosts were sacrificed one month later and 

 the genital tract accessories (albumen gland, ovospermiduct, copulatory 

 pouch, and the calcareous glands of the neck of the genital atrium) were 

 found considerably modified in comparison with the controls : while the 

 host had not increased appreciably in size, the genital tract had trebled ; 

 the genital tract in controls of the same age remained infantile. When a 

 fragment of ovospermiduct from a young Arion was recovered from the 

 general cavity of an adult Koheltia in which it had been implanted for five 

 weeks, the fragment had appreciably increased in size and had differen- 

 tiated histologically toward the type of structure found in the adult. Simi- 

 lar results were obtained on homotransplantation of the albumen gland be- 

 tween two individuals of Limax of different ages. Castration was success- 

 fully performed on adult Limax at an age of 10 months, when the genital 

 tract is fully developed. Three months afterward, appreciable regression 

 of different parts of the genital tract, particularly of the albumen gland, 

 had occurred ; regression of the penis was less marked. 



One additional area of possible endocrine function should be mentioned 

 here, that of the tunicates among which Carlisle has made some observa- 

 tions. An old report of Hogg (1937) on the occurrence of a gonadotropin 

 in the neural gland complex of tunicates when tested against the mouse 

 had not been widely accepted, probably because of the small number of 

 test animals involved ; Carlisle ( 1950) repeated these and additional tests 

 on male toads, also with small numbers of test animals, with results indi- 

 cating gonadotropic activity. More appropriately related to tunicate physi- 

 ology is an hypothesis proposed by Carlisle (1951) that the gonadotropic 

 hormone from the tunicate neural gland constitutes the afferent portion 

 of a gametokinetic reflex. The basis of this hypothesis is that injection of 

 human chorionic gonadotropin into Ciona and into Phallusia caused re- 

 lease of gametes from the gonads : injection of extract prepared from the 

 neural complex of 1,000 Ciona into 9 Phallusia provoked a similar response 

 in 6 out of 9 individuals. From the results of additional experiments involv- 

 ing the nervous system of tunicates Carlisle proposed that a hormone from 



