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 Charybdea, 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-paraffine 
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. 
