— 62 — 



the nucleus in the form of a horse-shoe. Further the mem- 

 brane grows in height and length simultaneously (tab. Ill, 

 fig. 35 and 39), the end of the basal thread severing from 

 the nucleus and freely sinking into the endoplasm. A long 

 series of succeeding stages in growth lead to the formation 

 of an amoeba possessing two nuclei, each of which is supplied 

 with a large membrane characteristical for types A and B 

 (tab. Ill, fig. 29), the nuclei being all the while connected by 

 the spindle. It is interesting to note that in the primary 

 stages of their formation the membranes lie wholly inside the 

 endoplasm and only afterwards project above the body-surface. 



Concerning the division of the plasmatic body of binuc- 

 leate individuals, I have only few data, but, probably, this 

 takes place by means of simple constriction. Three or four 

 times I found uninucleate amoebae of type 5, in which, besides 

 the undulating membrane, there was an outgrowth of the nucleus, 

 becoming gradually thinner towards the end. This was a part 

 of the spindle constricted (tab. IV, fig. 42). Evidently, such 

 stages present the results of a recently concluded division, in 

 the course of which the spindle is torn in two parts. The 

 fate of the spindle in individuals B is clear: it gradually beco- 

 mes absorbed. As concerns individuals of type A, I presume 

 that their axostyle is a direct derivative of the divided spindle, 

 which is not only preserved in this case, but grows further 

 in each daughter-individual. 



However (he case may be, it can be stated that the divi- 

 ding forms just described, which may be termed type D, give 

 origin to individuals A and B. 



Together Avith those tli^re are, however, to be found large 

 binucleate amoebae (tab. 11, fig. 21), which should be connected 

 with the uninucleate forms C, and. which I shall name as individu- 

 als of type E (tab. II, fig. 21). The shape, size and structure 

 of the ectoplasm of individuals E closely resemble that of the 

 individuals belonging to type C. The endoplasm is filled with food. 

 Lastly, in the body of the E individuals there are always two 

 nuclei of exactly the same structure as in the C individuals, 

 provided with the same small, delicate undulating membranes. 

 One of the nuclei lies near the very surface of the body and 

 the corresponding membrane projects to the exterior (tab. II, 

 fig. 25); the other nucleus with its membrane lies in the en- 

 doplasm in most cases. In the nucleus there is a karyosome, 



