194 Proceedings of the Royal Physical Society. 
alt may be a case of years to work out the Jife-history, and I doubt if 
any one could keep up the necessary conditions, environmental and climatic, 
which would admit of A. proteus passing through its complicated history 
which, without doubt, it does in its own chosen habitat.” 
While we are busy trying to achieve the possibly impossible, it seems 
to me that new names will only hinder where they are meant to help. 
In 1910, while a Research Student in Glasgow University, I undertook, 
at the suggestion of Professor J. Graham Kerr, the study of Ameba proteus. 
The first point in this study was to be an attempt to raise pure laboratory 
cultures of this amceba, preparatory to some elucidation of its life- 
history. 
For three years I worked assiduously on this one point, but regret to 
state that I was not successful to the extent I had planned. I worked 
with small numbers, and from the many cultures of small numbers which 
I did succeed in raising and keeping for a time, the longest pedigree actually 
traced was of six months’ duration. This “existence” of the culture was 
uneventful but for the multiplication by division, watched in many cases, 
and carefully noted in all. No encystment took place, nor could it be 
induced artificially, although the period of successful culturing was from 
November to May, thus including the months during which the amoeba 
naturally encysts. The three years were not wasted; a case of mitotic 
division* was obtained as also the natural encystment? of A. proteus, both 
facts helping considerably in the general summary here recorded. 
It would seem that the greater part of the work on A. proteus has been 
carried out upon the large amoeba described by Leidy*® under this name, 
without reference to the peculiarities in structure, etc., which present 
themselves only to the constant and careful observer. These differences 
are revealed by Leidy himself in his excellent illustrations and in his text, 
but he makes no reference to them as of any specific importance. 
My own work was commenced under the same impression, that all the 
large amcebee described as A. proteus by Leidy were alike in all respects, and 
my attention was not aroused to their dissimilarities until the food question 
forced itself upon me. : 
The excellent work of Allen and Nelson‘ on the culture of diatoms, published 
about this time, seemed to open a door for an attempt at the pure culture 
of A. proteus from the well-known fact that A. proteus feeds on diatoms. 
1 Carter, Roy. Phys. Soc. Hdin., vol. xix., No, 4, 1913. 
2 Pod, ‘ * vol: xix: No, 8, 1915: 
> Leidy, Freshwater Rhizopods of North America, 1879. 
* Allen and Nelson, Q.J.M.S., 1910, vol, 
