40 JOHNS HOPKINS UNIVERSITY MORPHOLOGICAL MONOGRAPHS. 



oral lobes. The animal pulsated well enough, but the contractions 

 seemed not so simultaneous in all parts of the margin as normally. 

 After a few days it had partly regenerated but died. One of the oral 

 lobes cut off had some power of contraction, and this some time after 

 the operation. A similar cut, but semicircular, made no difference 

 between the contractions of the two halves. 



53. The whole region of the sensory clubs was cut out when the 

 animal was not seen to pulsate again, except in the evening, when 

 pulsations were observed. The oral lobes also moved. 



HISTOLOGICAL. 



Method. The following results on the histology of the sensory 

 clubs, their eyes, and the tentacles, as already noted, were obtained 

 from some of Dr. Conant's preserved material. These results relate 

 almost wholly to Chary bdea, with only a few references to Tripedalia, 

 noted in their proper place. 



A portion of this material was killed after keeping the animals 

 in the dark for some time, for the purpose of discovering any 

 changes in the pigment of the eyes. I believe that a retraction 

 of the pigment of the long pigment cells that project between the 

 prisms and pyramids of the vitreous body in the retina of the distal 

 complex eye is very evident in eyes killed in the dark. (But more 

 on this below.) 



I obtained my best results from the material preserved in 

 saturated corrosive sublimate, to which had been added (5 to 10 per 

 cent.) acetic acid. This- also was Conant's experience in his previous 

 work on Charybdea and Tripedalia. 



My best sections were obtained by embedding the sensory clubs 

 in celoidin, passing the little blocks of celoidin with the sensory 

 clubs into chloroform until perfectly transparent, and then into 

 paraffine. I then cut sections as we ordinarily cut paraffine sections, 

 mounted and stained them on the slide. My purpose in using this 

 method was to avoid the displacement of the vitreous bodies of the 

 eyes during embedding and cutting. This object was fully realized 

 and more besides. Since the sections cut by the celoidin-paramne 

 method gave me so decidedly the best differentiation of the axial 

 fibers of the retinal cells, as also of the cilia, basal bodies, etc., I am 

 inclined to believe that the celoidin was in part responsible for this 

 differentiation. 



