596 THE AMERICAN NATURALIST. [Vol. XXXVII. 



firm this view of Doflein's, nevertheless in one or two cases there 

 seemed to be a distinct engulfment of the primitive ova. It 

 appears to me that neither theory alone explains all the phenom- 

 ena involved in the growth of the ovum, but that a combination 

 of both theories would better explain the facts. My observa- 

 tions, however, lead me to agree with Doflein in his objection to 

 the term "amoeboides Fressen." If we watch an Amoeba in its 

 movements, we will observe that when a process of the proto- 

 plasm presses against certain foreign particles of organic nature, 

 they become sunk in the substance and pass gradually into the 

 interior. Here they become surrounded by a little globule of 

 watery fluid, a vacuole ; and by degrees these particles partially 

 or wholly disappear. All the matter which is capable of it 

 becomes digested and assimilated by the protoplasm. It is very 

 probable that the vacuole contains some ingredient of the nature 

 of a ferment which is capable of acting upon these foreign sub- 

 stances and rendering them more soluble. These are the phe- 

 nomena involved in the process of amoeboid eating. Yet, while 

 they agree in a few respects with those phenomena which are 

 exhibited in the growth of the ovum, on the other hand, it seems 

 to me that they present such fundamental differences as not 

 entirely to warrant the statements of Balfour and Tichomi- 

 roflf. In the first place, there is no formation of a vacuole 

 about the absorbed cells, with the exception of, later on, a small 

 one about their nuclei. I did not find these vacuoles in any sec- 

 tions of Corymorpha, but in examining some slides prepared by 

 Miss Allen (:oo) in her study of the development of Titbit /aria 

 crocca, I found numerous cases of these vacuoles containing, 

 from one to as many as seven or eight nuclei. These vacuoles 

 however, were all found in ova which had begun to segment, and 

 undoubtedly the same phenomenon would have presented itself 

 in Corymorpha, if the material used had been of a later stage 

 of development. Doflein ('96) describes the same thing in 

 Tu bit /aria larynx. 



Furthermore, the cytoplasm of the absorbed cells simply min- 

 gles with that of the growing ovum, and undergoes no apparent 

 change whatsoever. There is no process of absorption, the cell 

 walls disappear gradually and the nuclei appear to have been 



