238 Journal of Comparative Neurology. 



Carcinus and Hydrophilus that (a) an impulse can be conducted 

 along the entire length of the ventral cord along one side only, 

 i, e., through the longitudinal commissure of the side receiving 

 the stimulus in such manner as to call forth a locally (definitely) 

 directed reflex action, (b) The transverse commissures of each 

 ganglion are the only paths along which an impulse calling forth 

 a locally directed reflex action can be transmitted from the 

 stimulated side to the other one. 



The Functions of the Otocyst. A Review. 



By E. P. Lyon. 



Up to the year 1887 it was generally believed that the 

 otocyst as found in invertebrates was an organ of hearing. The 

 resemblance of the capsule, with its sensitive hairs and otolith, 

 to the ear of vertebrates was the main ground for this belief. 

 Indeed "the otocyst was regarded as a reduction or rudimen- 

 tary state of the membranous labyrinth." After the develop- 

 ment of a definite theory of equilibrium and geotropic functions 

 for the vertebrate ear, it was natural to expect that similar 

 functions were subserved by the invertebrate otocyst. Some 

 of the work which has been done in support of this view I 

 shall briefly review. 



I. The first paper, that of Delage, Stir tine Fo?iction noii- 

 velle des Otocystes, appeared in the Archives de Zoologie Expc'ri- 

 vicntalc et Gene rale in 1887. 



After trying moUusks of various kinds with little success, 

 he turned his attention to crustaceans. A description of the 

 behavior of two species will be sufficient to serve as a general 

 index of Delage's work. The schizopod Mysis has its otycysts 

 in the inner plates of the four-parted tail. The cysts could 

 therefore be removed with ease. On account of their distance 

 from the more delicate parts of the central nervous system the 

 operation would seem likely to be free from severe shocks and 



