REPRODUCTION 35 



course become quite familiar through the classical 

 experiments on Paramcedum, but its occurrence 

 following on the artificial stimulation we have 

 employed emphasises the influence which auxetics 

 undoubtedly have upon the chromatin of the living 

 cell. We have observed the presence of minute 

 amcebulse, similar to those we have seen produced 

 by conjugation, on some twenty occasions during 

 nine months, and they occur almost invariably, if 

 not always, in cultures in which simple repeated 

 divisions of the amoeba do not appear adequate to 

 maintain the species. The process of conjugation 

 is as follows : Two amcebse in which we were 

 unable to distinguish any difference in size or 

 morphology, gradually came into contact and 

 adhered. In course of time they merged into each 

 other, forming a sac, which we call a " conju- 

 gation cyst," and which is difficult to distinguish 

 from the ordinary resting cysts, although it is 

 somewhat larger and the wall is thinner, and the 

 appearance gives one the impression of a bladder 

 full of fluid. The sac formed in this way remains 

 perfectly quiescent for many hours, and then bursts 

 quite suddenly, liberating a glairy, faintly yellow, 

 liquid. If this is watched carefully for a consider- 

 able time with a high power and perfectly central 

 illumination, innumerable minute granules gradu- 

 ally appear. These slowly grow larger and begin 

 to exhibit vacuoles and pseudopodia, eventually 

 becoming typical, very active, small amoebulse. 

 We were unable to distinguish the nuclei in the 

 gametes and think that they had broken up into 

 chromatin masses. The phenomenon which we 

 observed was obviously not due to agglomeration, 



