1893. NUCLEUS IN UNICELLULAR ORGANISMS. 177 
endeavour to study alone the behaviour of the nucleus, both before 
and during, as well as after, the various steps in the cyclic changes 
undergone by this cell. 
A magnification of from 5,000 to 6,000 diameters was found 
efficient for this, and with the life-history of the cell known, it was 
less difficult to trace by themselves the nuclear changes. 
In studying these, it is only the changes occurring and observed 
in the living organism, and during its life, that have proved of any 
real value. The effect of desiccating and staining these saprophytes 
was in all senses unsatisfactory ; the details were too minute, or too 
delicate to admit of this treatment, for whatever method was adopted, 
the results, as compared with the living form in the same stage, were 
simply unintelligible and useless. But this could only be really seen 
by comparison of the results of the same phenomenon in the living 
organism, and in the dried and stained state. 
Nevertheless, by using a one-and-a-half per cent. of acetic acid, to 
which varying quantities of methyl-green are added, a decided 
strengthening of the special nuclear features was effected. Thus the 
nuclear envelope seen in most stages of its activity is much 
strengthened, and so were the beaded threads embedded in the nuclear 
hyaloplasm ; and little, if any, inconvenience could be seen to result 
in the organisms. 
In the inactive stages of the organism, or when no cyclic changes 
were manifest, the nucleus was hyaline, or at least exhibited nothing 
but the faintest traces of a colourless reticulation when very critically 
examined. This simple state of nuclear hyaloplasm is seen in Fig. 13, 
representing a portion of the body of the organism and the nucleus, 
the latter magnified 5,000 diameters. 
By steadily watching a form in this condition, it would in all 
probability be seen to become more marked in its granulation, and at 
length what appeared like a delicate thread of beaded structure 
became more and more visible, occupying at first the circumference 
and at length the whole plasm of the nucleus, as shown in Fig.14; but 
when this was complete a distinct line, made more visible by methy]l- 
green, appeared, as shown in the nucleus of that figure. No indica- 
tion of any division anywhere in the body of the organism had yet 
appeared. Now, however, it soon becomes manifest that the complex 
foldings and twistings of the beaded thread in the nucleus condense 
on either side of it, leaving the dividing line in a hyaline space, as 
shown in Fig. 15; and now for the first time a line appears at a and 
opens, so that the fission of the body has begun. 
After this the process is rapid, occupying only three or four 
minutes. The nucleus opens as in Fig. 16, where it is seen apart 
from the body, corresponding to the stage seen in Fig. 2, D, rapidly 
passing into the condition seen in Fig. 17, corresponding to the 
state shown in Fig. 3, E, and where the fine-beaded thread appears 
to be drawn out, connecting the still dividing nuclei; but in this 
N 
