206 Proceedings of the Royal Physical Society. 
A. proteus Pallas, A. nitida, and A. nobilis; the basis of differentiation 
being apparently size and nucleus. From his illustrations and text these 
three “species” would fall under the letters Y, Y and Z of the suggestion 
here offered thus—A. proteus Pallas agrees with A. proteus X; A. mtida 
with A. proteus Y; A. nobilis with A. proteus Z. The fold in the nucleus 
of A. nitida Penard is not constant, and from what I have observed is only 
present in older cultures of A. protews Y. The nucleus is not normal — 
when this infolding is present to such an extent. I find that Scheeffer has 
noted this also. A. nobiizs is the multinucleate form. 
In 1904 Awerinzew! described, as already mentioned, mitotic division 
in A. proteus Pallas. He did not otherwise describe the amceba; however, 
he told me that all the amcebe upon which he had worked were A. proteus 
as described and figured by Leidy. The same answer was received from 
Dr Stolc.2 I have little doubt but that the amceba studied by Awerinzew 
was A. proteus Y, while Stole’s drawings show that he observed both 
X and Y, and his descriptions reveal that he induced the Z condition in Y. 
I have to thank both these eminent men for their courteous attention 
to any question I have put to them on this subject. 
An excellent resumé of the nomenclature of A. proteus, by Cash and 
Hopkinson,® was published in 1905. They give good illustrations of the 
amoeba here called A. proteus X under the title of A. proteus Pallas, and 
with the following remark place A. proteus Y of my scheme as a variation :-— 
“The nucleus and the contractile vesicle are normally as in A. proteus, but 
in general aspect and mobility this form is so distinct as to raise a doubt 
whether it really belongs to this species; Leidy, however, figures it as a 
form of A. proteus and it may for the present be distinguised as var. 
granulosa.” 3 
These authors neither figure nor mention the multinucleate form of 
A, proteus as such, but evidently put it into the Pelomyxa group under 
Cernyz’s A. princeps and Brayley’s A. proteus. One point, however, is to 
be noted, that they figure A. villosa with the nucleus of A. proteus. If there 
is a point of radical difference between A. proteus Pallas and A. villosa 
it is the nucleus; when, therefore, this difference ceases to exist, I should 
unhesitatingly place A. villosa, with the diatom-feeding form of A. proteus 
as found in stagnant pools. The villous tuft is by no means special to 
A, villosa so called, nor is it always present in that organism itself; as 
a matter of fact when many amcebe in a culture show this phenomenon, 
1 Awerinzew, loc. cit. 
2 Stole, loc. cit. 
* Cash and Hopkinson, “British Freshwater Rhizopods,” London, Roy. Society, vol.i., 1905, 
