202 Proceedings of the Royal Physical Society. 
The formation of reproductive cysts has only been observed by me, 
to my own satisfaction, in the case of A. proteus X, but I have watched 
strange isolated incidents in the behaviour of the other “types.” The 
cyst described by Scheel! may be that of A. proteus Y or even A. proteus Z. 
No description of the free amceba is found in the text. So far then it 
would seem that— 
A, proteus X multiplies by division (mitotic 2) and by encystment.® 
A, proteus Y multiplies by division (mitotic * and amitotic °). 
A, proteus Z divides as a plasmodium. 
LOCALITY AND HABITAT. 
Material was obtained from as many localities as possible, special note 
being taken of the type of A. proteus and the season of the year when found. 
In some localities all three types were to be met with, sometimes together 
at other times one type alone over a long period of time. 
Mr Bolton of Birmingham was my main source of supply until 1916, 
sending material from Lapworth (pond), Sutton (ditch), Baddesley Clinton 
(pond), districts around Birmingham, England. Locally I obtained supplies 
from Wishaw, making my first find in the River Auchter there, also from 
Milngavie; and excellent specimens were received from Ireland, Killarney 
giving the best and most numerous. 
The three types will live together in the same environment, but while 
A. proteus X will thrive upon a diet similar to that of the two other types 
it apparently prefers diatoms in addition when they are available. Occasion- 
ally A. proteus X may be found in few numbers with Y and Z, but as a rule 
when present it holds the field for numbers. <A. proteus Y and A. proteus Z 
are often found together, in fact one may say always. A. proteus Z is found 
with A. proteus X in large numbers in certain seasons of the year. I have 
particularly noted autumn, about October. 
At the outbreak of the war in 1914, other work prevented me from continu- 
ing an uninterrupted study of A. proteus, and also from collecting ; thus my 
best thanks are due to my colleague Sister Monica Taylor, D.Sec., and her 
staff of the Zoology Department for their great help in finding sources nearer 
home and in keeping up the supplies of amcebee for me. The results of the 
collecting and culturing of amcebee have been embodied in a short paper by 
Sister Monica, to which I refer the reader. 
1 Scheel, Kupffer’s Festschrift, 1899. 
2 Carter, loc. cit. 
3 Ibid., loc. crt. 
4 Awerinzew, loc. cit. 
> Stole, loc. cit. 
