176 NATURAL SCIENCE. Marcu, 
In the course of from five to seven minutes there would supervene an 
amoeboid condition, not striking, but still visible, as shown in H, Fig. 
6, where the body-substance would oscillate from the hollow condition 
shown to the lateral expansions indicated by the dotted lines at s, ¢, a 
vacuole—curiously like an ‘‘ eye-spot ’’—would appear, exhibiting very 
marked opening and shutting, as at v; and the nucleus, «, was driven 
to the middle of the body, greatly enlarged, and, losing its nucleus- 
like aspect, was torn apart in irregular halves; meanwhile, a very 
strong sigmoid division-line, shown in J, Fig. 7, at w, x, became 
extremely marked, and the divisions of the nucleus were pushed one 
on each side of this line, as at wand x. At this time a point of pro- 
toplasmic material was pushed out, as at y, dividing into two fine 
threads. 
A gliding motion now ensued, by which w glided off from x ; 
this is seen at Fig. 8, x, a, 8, showing two normal forms nearly freed 
from each other in this way; but in our earliest work it was quite 
manifest that the nuclei of these two forms had quite strikingly 
changed, having undergone some radical alteration, and trailing 
flagella were formed at z, partly by growth and partly by division. 
Soon after total freedom from each other, these modified forms 
swam freely for some minutes, and then directed their motion to 
some part of the field where the ordinary forms (with the usual 
nuclei) were in greatest abundance, and almost immediately what 
was seen to be an act of fusion commenced. The initial stage is 
shown in Fig. 9, L, where the unlikeness of the nuclei is seen at 
y, 6. 
The fusion takes place rapidly up to a certain point, for in 
eight minutes a large part of the body-substance of each has fused 
with the other, as seen in 10, M, where the nuclei are fully united, 
and a radial or star-like diffusion takes place, as seen in 7; and this 
continues, growing fainter and less perceptible for an hour, or some- 
times an hour-and-a-half, until it wholly disappears, and all trace of 
nucleus is gone, the mass of the plasm of the combined cells being 
faintly granular, or perhaps reticulated; but the trailing flagella (6) 
fuse together and unite with the body, which now rapidly changes, so 
that in the course of fifteen minutes it assumes the shape and con- 
dition shown in Fig. 11, N. At the end of four hours a kind of 
pulsating movement shows itself in this triangular sac, and at length 
it burst one or two, and sometimes (as in Fig. 12,0) the three corners 
of the triangular sac, and an enormous number of semi-opaque and 
extremely minute particles, escaped (Fig. 12), and by watching these 
they were seen to pass by growth into forms corresponding to the 
common form from which they arose. 
These observations were made in the original and renewed study 
of the behaviour of this organism as a whole; but during the past 
three years the greatly superior microscopic apparatus, both illumi- 
nating and image-forming, placed at our disposal, has led to an 
