Anatomy o/* Stephanoceros Eichhornii. 5 



the nervous ganglion is a peculiar organ consisting of large 

 clear cells lying at the back of the vestibule near the dorsal 

 surface. Above it and well under the dorsal surface is a 

 three-lobed, granular, semiopaque body with which the 

 nervous ganglion is possibly connected. The nervous gan- 

 glion in many of the Rotifera, especially among the Notom- 

 matadje, shows a marked cellular structure at the lower end 

 which loses itself in a granular, semiopaque, upper portion ; 

 but it must be admitted that if these peculiar bodies constitute 

 the nervous ganglion of Stephanoceros, it is rather their position 

 than their shape and structure that would lead us thus to 

 interpret them." Mr. Cubitt (6) says, "It [the brain] is seated 

 in the anterior region in a dorsal aspect ; it is pear-shaped, 

 constricted in the middle, where it supports certain small 

 processes which traverse its substance as well as project be- 

 yond. In active individuals the brain is large and prominent, 

 but less conspicuous in others, whose sluggish movements 

 indicate disease or age ; its structure is not granular, except 

 at its internal attachment, and is in no way related to the 

 granular layers that occur on each side of it. It presents 

 more the appearance of a cellular structure, but differs essen- 

 tially from the character of such a structure . . . the divisions 

 incline to a pentagonal arrangement, and each junction or 

 union of the fibres is distinguished by a definite nucleated 

 swelling, faintly resembling Gratiolet's figures of the nerve- 

 cells of the spinal cord." My own observations show the 

 li brain " to be a somewhat cylindrical organ, and the walls to 

 be composed of irregularly-shaped oval cells, each possessing a 

 nucleus and nucleolus. Each cell is wholly or partially rilled 

 with granular protoplasm, and as the secretion present in the 

 central space is also granular, one may fairly assume that the 

 granules originated from the cells and that the cells were in 

 an active state at the time of the death of the animal (vide 

 PI. II. figs. 13 and 14). The function of this organ will, I 

 think, be easily demonstrated if we examine the living animal. 

 Dr. Hudson (loc. cit.) says, " From the spot where it [the brain] 

 adheres to the wall of the vestibule a sort of protrusile tongue 

 or taster rises, which can be pushed forward so as nearly to 

 fill up the interval between the knobbed ciliated ends of the 

 ciliary wreath. This tongue may be seen incessantly pressing 

 backwards and forwards as the food passes into the vestibule, 

 as if discriminating between the passing atoms, just as the 

 two tasters do in M. ringens.' n Examination of transverse 

 and longitudinal sections shows that the cylindrical organ 

 previously described is open at the upper end, where it com- 

 municates with a definite single tube enclosed by thin mem- 



