186 INVERTEBRATE PHYSIOLOGY 



crustacean could be explained on the basis of one hormone or was due to 

 a number of hormones. In brief summary, Brown and a number of collabo- 

 rators (see Brown, 1952, for specific citations) have reported three chro- 

 matophorotropic principles from the sinus gland of crustaceans, the dis- 

 tinction being based to some extent on dififerent solubilities in ethanol and 

 on the response of particular chromatophore types in different crustacean 

 species : ( 1 ) a principle which causes concentration of the red chromato- 

 phores of Palaemoneies, (2) a principle which causes dispersion of the 

 black chromatophores of Uca, and (3) a principle which causes the black 

 pigment in the chromatophores of the telson and uropod of Crago to be- 

 come concentrated. From the central nervous system of a variety of crus- 

 taceans two additional principles were adduced: (4) one which disperses 

 the melanophore pigment of Crago both in the body and in the "tail," and 

 (5) one which concentrates the melanophore pigment of the body of Crago 

 but not of the "tail" of Crago. 



Most of the evidence presented in attempting to settle the problem of 

 localization of the chromatophorotropic hormones of the eyestalk and of 

 the central nervous system has consisted of histological demonstration of 

 apparent neurosecretory structures in the central nervous system and of 

 injection experiments involving extracts prepared from the central ner- 

 vous system. The recent explanations of the part played in molting and its 

 associated metabolic processes by the X-organ were facilitated by de- 

 ficiency experiments involving removal of the sinus gland; the advisa- 

 bility of similar deficiency experiments in studies of color change would 

 seem apparent. 



As long ago as 1940 Brown reported that most of the chromatophoro- 

 tropic effect of whole eyestalks of Palaemoneies and Uca was contained in 

 the sinus glands. A study by Brown, Ederstrom, and Scudamore (1939) 

 neatly complemented the early injection experiments by examining the 

 effects of surgical removal of the sinus glands from the eyestalk in Palae- 

 moneies on the animal's subsequent color behavior. These authors found 

 that the glands could be removed without apparent serious disturbance to 

 the rest of the eyestalk. In such Palaemoneies it is to be expected that the 

 erythrophores will become dispersed and the animal will remain in the 

 dark phase of its color range if the sinus gland is the chief source of a 

 chromatophore-concentrating principle; in addition the animal will be 

 unable to adapt its erythrophores to an illuminated white background. 

 When 16 such operated animals were tested on an illuminated white back- 

 ground, the erythrophore responses were such that the animals fell into 

 three groups : 5 showed no concentration of the red pigment, remaining 

 permanently dark ; 4 showed a weak concentration of the red pigment ; 

 and 7 underwent strong concentration of the erythrophores. Thus, only 



