58 CALIFORNIA ACADEMY OF SCIENCES. 



equally distinct, centrally situated round nucleus. The 

 large knobs terminally situated on the tentacles usually 

 contain more of the cells than do the lateral ones. 



That we have here one of the tentaculiferous Infusoria 

 I think there can be no doubt, but I have been much 

 puzzled to know what interpretation to put upon several 

 appearances presented. It may be supposed that the 

 cells described as being- situated within the knobs are the 

 anamalcules that have made their wav into the tissue of 

 the host, and that the knobs are produced as a patho- 

 logical growth from the infected tissue. The parasite 

 might then be regarded as belonging to the genus Sphce- 

 rophrya of Claparede and Lachmann. However, there 

 are several difficulties in the way of this view, one of 

 which is, I think, fatal in itself. It will be noticed that 

 the tentacles (of the parasites, for such undoubtedly are 

 the structures which I have described above as " coarse 

 cilia") are always situated, not on the cells embedded 

 in the knobs, but clearly on the knobs themselves (figs. 

 16b and 17, pi. ii). 



The explanation that seems to me to be most in accord 

 with the facts observed is that the knobs, whether ter- 

 minal on the tentacles of the host or otherwise situated, 

 are the foreigners, and that the contained cells described 

 are endogenously produced spores. 



The terminal knobs are so perfectlv continuous with 

 the tentacle of the host itself that it is impossible, in any 

 instances which I have seen, to fully satisfy ones self that 

 the whole structure is not a tentacle. Furthermore, I am 

 not able to find with certainty the nucleus in what would 

 be, according to this view, the parent infusorian, though in 

 the specimen shown in fig. 17 it may be present as a 

 deeply stained irregular structure shown at ir. The 

 cavernous spaces seen occupying the whole central por 

 tion of this knob I suppose to be contractile vacuoles. 



