Some Observations on Amceba proteus. 207 
as I have seen XY, Y and Z do at times, I suspect the culture, or some other 
environmental condition. 
Calkins’! paper, giving a “probable” life-cycle of A. proteus introducing 
a sexual generation, appeared in 1904. However this life-cycle may be 
regarded, it is quite certain that Calkins worked with genuine A. proteus— 
Y and Z of my scheme. When, however, he comes to the large primary 
nucleus and small secondary nuclei in the cyst, I am seriously inclined 
to think with others that he is dealing with a parasite. At the same time 
I do not hold with Schubotz? who, writing in 1905, says that Calkins 
probably worked on A. villosa, and Awerinzew on a third variety, while 
he, Schubotz, claims to have worked on A. proteus Pallas. It depends 
upon which amceba is to be called A. proteus Pallas. My observations 
lead me to think that Schubotz certainly saw A. proteus XY among others, 
but from his illustrations his research was mainly, if not wholly, carried out 
upon A. proteus Y. As for Calkins’? amcebe; they were by no means 
A, villosa, as usually described. His micro-photographs and text descriptions 
make it quite clear that the specimens he dealt with were A. proteus Y and 
A. proteus Z. His own remark is :—“ While A. proteus has an average size 
of 300 », the individuals upon which I worked were somewhat larger than 
this, although in the same culture there were smaller and typical forms; 
in short, the general appearance was not different from that of Ameba proteus 
under ordinary circumstances of scarcity of food.” What were the smaller 
and typical forms ? | | 
Schubotz summary of the work done on A. proteus, especially the 
nucleus, is good, but, like myself, he finds it difficult to follow where no 
description accompanies the paper. He complains of Klemensicx, among 
others, who, he says, “omitted to give a description of the amceba form which 
he studied. He speaks of A. proteus without sketch or description of its 
characteristics. It remains uncertain whether I am studying the same form 
as he.” This doubt accompanies almost every paper on 4A. proteus when 
time has been devoted to a study of the living material. 
1906 brought Stole’s* work of years on the inducement of the multi- 
nucleate condition in one of the uninucleate forms of A. proteus, with a 
suggested and most probable life-history, perhaps one of the clearest 
connected stories of all hitherto produced. 
1 Calkins, Arch. fiir Protist., vol. v., 1904. 
2 Schubotz, Arch. fiir Prot., vol. vi., 1905. 
3 Calkins, loc. cit. 
4 Stole, loc. cit. 
VOL. XX. ik 
