200 Proceedings of the Royal Physical Society. 
have I found a specimen in a binucleate condition, and on both occasions 
I was able to conclude from convincing evidence that it was a question 
of delayed division. The single nucleus is spherical, as a rule, the 
nuclear membrane being filled with coarse granules approximately equal 
in size, spherical in shape, and evenly distributed. Occasionally I have 
found an oval nucleus in this amceba, showing, when rolling over the well- 
known clear lens-like space between the chromatin and the nuclear membrane 
at the poles of the short axes, the discoid nucleus, so general in A. proteus Y 
but rare in A. »roteus X. 
In the A. proteus Y series a variety of nuclei may be met with, the 
members are, however, as a general rule, uninucleate, as A. proteus X, but 
individuals may often be found, seasonally it would seem, in the binucleate 
condition, which in this amceba is not necessarily a case of delayed division. 
However, if the nuclei present in a specimen of this series exceed two in 
number the amceba passes, according to my hypothesis, into the class of 
A. proteus Z. The single nucleus is oval in outline, the granules varying 
in size according to their arrangement in the individual nucleus. If this 
arrangement is ag in A. proteus X, then the granules are generally less 
coarse than is usual in the nucleus of this amceba; if submembrane blocks 
are present, and a large central mass of granules, then these latter are much 
larger and not equally spherical in form. 
When the binucleate condition arises, either naturally or by inducement 
(Stole),2 both types of nuclei may be present in the same specimen, 7.¢. the - 
nucleus of .A. proteus X and .A. proteus Y. I have found ‘this in nature 
myself, and consider it significant. But in this series the variations of the 
nucleus are many and seem in some way graded with the other characteristics, 
and are at present under consideration. 
In the multinucleate A. proteus Z, there is little doubt as to the similarity 
between the individual small nuclei and the single nucleus of A. proteus Y 
and frequently also of A. proteus Y, an interesting fact if nothing more. 
Vonwiller? says that he has never found an amceba of the multinucleate 
type in the uninucleate condition. I can only say that each year I find 
it more difficult to reconcile myself to the idea, held by many, that the 
multinucleate form A. proteus Z does not arise from the uninucleate 
A, proteus Y or even A. proteus X. Dr Stole has induced the multinucleate 
condition in A. proteus Y, and I have preparations of these amcebz possessing 
1 T will not discuss the “‘ ovoid” or ‘ discoid” forms—Scheefter has done this in Science, 
loc. cut. 
2 Stole, “ Plasmodiogonie,” Arch. fiir Entw. der Organismen, Bd. xxi., Heft 1, 1906. 
3 Vonwiller, loc. cit. ' 
