88 PROTOPLASM 



easily made out that they are lodged in the nodal points of 

 the protoplasmic meshwork. The anterior edge of the house 

 appears to pass directly into the pellicle of the anterior part 

 of the body projecting from the shell. 



The living macro - nucleus (inn) also shows the reti- 

 cular structure very plainly, more so, in fact, than the pro- 

 toplasm, since the framework of the nucleus is rather 

 darker and its meshes are a little wider. The external 

 limiting contour of the nucleus is somewhat dark and 

 sharp, like the pellicle. The more external layer of nuclear 

 meshes bordering on it is directed radially to the surface, 

 and hence shows the relations of an alveolar layer. In the 

 nodal points of the nuclear framework numerous dark 

 strongly refracting granules can be made out, doubtless 

 chromatin granules. 



I did not investigate the tentacles more closely, but 1 

 was able on the same occasion to examine those of ToJco- 

 plirya (PodopJirya) elongata, Clp. and L. Their optical 

 section gave the appearance represented on Plate XII. 

 Fig. 5. The central circle is the optical section of the 

 central canal, and the radially striated zone is a single 

 layer of meshes of protoplasm which forms the wall of the 

 tentacle. 



Ciliata 



On Ciliata I have recently made but few observations, 

 although, as was known from earlier researches, they are 

 especially suitable objects for the questions in view. 



I observed the protoplasmic structure in the living condi- 

 tion very distinctly in a small, somewhat yellowish, undeter- 

 mined marine species of VorticcUa, which was of common 

 occurrence on Rhizopod shells coming from Naples. If a 

 spot at the margin, slightly behind the peristomial ridge of 

 the living Vorticella, be studied in optical longitudinal section 

 (Plate IV. Fig. 5), there is seen most externally the rather 

 thick, double contoured, dark pellicle (p), and below this 

 the clear alveolar layer (alv), the radial striation of which 

 shows up but feebly, though it is quite recognisable. Upon 

 this follows the internal reticular protoplasm with distinct 



