56 Proceedings of the Royal Physical Society. 
temperature of 60° F. On returning to examine what I hoped would 
be perfect cysts, I found instead a mass of amoebe, and before ten days 
were over the numbers had increased to hundreds. Division had evidently 
been taking place; consequently, a great number of preparations were 
made, with a memorandum to examine for stages in nuclear division, 
especially in the sectioned specimens. No case of mitotic division was 
found in any of the numerous whole preparations, and only the one 
figured in this paper was found among the sections. 
This particular specimen, differing in no external respects from its 
neighbours in the same section, was, as they also were, slightly smaller 
than the ordinary extended A. proteus, being roughly 150 » in 
diameter. 
When in an almost spherical condition and about to divide, the amoeba 
puts out short blunt pseudopodia, very slowly, all round its body, lengthens 
slightly (cf. Fig. 2), and about fifteen minutes after this first indication of 
lengthenine—as mentioned above—the final strand of protoplasm snaps 
across and the two daughter-amoebe move away from each other. This 
is well to remember, as to fix an amoeba when the bridge of protoplasm 
is already formed entails a fruitless search for mitotic figures. The 
capture must be made before the roughly spherical form is lost, and 
during the first indications of lengthening, since the mitosis is apparently 
at its height by this time. 
THE NUCLEUS. 
Before proceeding to a detailed description, it might be a help to the 
correct reading of the figures, to state that the nucleus in question has 
been sectioned somewhat obliquely, as is clearly shown by a reconstruction 
with glass plates. This obliquity affects the appearance of the sections, 
but particularly that shown in Figs. 2 and 2a, civing a false impression as 
to the position of the apices of the cones of the spindle; the first section 
of the series, which shows no portion of the spindle, is not figured. 
Contrary to Awerinzew’s! account, the nucleus has not assumed the 
form of an Ellipsoid of Rotation, the flattening, if such there be, has 
taken place in a plane parallel to the spindle axis and not at right angles 
to it. 
Apart from the fact that it is in the metaphase of mitosis, the condition 
of the nucleus as a whole is remarkable. The persistence of the nuclear 
membrane in its entirety is interesting, as Lawson? holds that this 
1 Awerinzew, loc. cit. 
2 Trans. Roy. Soc. Hdin., vol. xlviii., part 1. (No. 7), p. 140. 
