642 0. CLIFFORD DOBELL. 



exists between degenerative and " sexual " processes. Be- 

 sides the fact that chromidia are formed in both^ we have 

 the observation that an amoeboid condition may occur in 

 degenerating Protozoa, and also sometimes just before 

 conjugation. Fusion also occurs in degenerating forms of 

 various kinds. I have observed it especially in flagellates, 

 e.g. Trichomastix, Trichomonas, etc. Senile Para- 

 moecia enter upon what Calkins calls the ^^miscible state,^^ 

 when they tend to adhere to one another. Similarly, Koux 

 has observed that isolated, living blastomeres of frog's eggs 

 become amoeboid and run together; though, according to 

 Driesch, this is merely due to the capillary forces between 

 the cells. These facts, and many others of a similar nature, 

 are not without interest, both from a pathological and from a 

 zoological point of view. I may mention merely their pos- 

 sible bearing upon the remarkable fusion which appeal's to 

 take place between leucocytes and cancer cells, and its un- 

 known significance. And since the work of Calkins seems to 

 indicate that chemical change in protoplasmic composition is 

 the chief beneficial effect of conjugation, and there is some 

 proof that Protozoon individuals have chemical compositions 

 differing from one another (cf. Jensen), is it not at least 

 possible that the physico-chemical changes which cause 

 fusion in degenerating cells are of a similar nature to those 

 which gave rise to the first cell-couplings, and which still 

 determine the fusion of one gamete with another ? 



Zoological Labokatoey, 



Cambridge. 



Addendum. 



Neresheimcr's full account of the life-cycle of Opalina 

 has appeared since this paper was submitted for publication. 

 It is a very complete description, with full references to the 

 literature, and is to be found in 'Arch. f. Protistenk :' Supple- 

 ment i (Fcstband fur K. Hertwig), 1907, p. 1. 



