672 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
astonishing degree ; and, therefore, I would argue that by its careful 
study, and by the study and comparison of kindred unicellular organisms, 
we shall find nuclear complexity in its least complex condition, and, 
therefore, more capable of guiding us amongst the perils of the karyo- 
kinetic figures of the cells of tissues with vast biological histories and 
long biological inheritance. 
Nor is this all. They may be studied in their living condition, and, 
I will add, only with efficiency in that condition. Stains may be to some 
extent used without destroying the organism, and by patience and a 
thorough knowledge of the nature and use of objectives and condensers, 
facts of immense value can be made out. 
What we want to discover is, what determines the changes in so 
lowly and minute a nucleus, and what are the correlations between the 
changes in the nucleus, and the powerful changes brought about in the 
minute unicellular organism. 
The entire organic cell, with a complete life-history definitely known, 
if relatively large, may be, say, the one-thousandth of an inch in breadth 
and thickness respectively. Cubically it occupies the four- thousand- 
millionth of a cubic inch. 
The nucleus may be the one-tenth part of this cubically. Yet with- 
in this area all the determinate causes of vital phenomena of the whole 
unicellular organism are at work ; and what is more, they are accessible 
to our perception through modern instruments — and those, when properly 
used, are instruments of precision. 
So far as my present ability and instruments carry me, when the 
organism is in a fixed or static condition, whether for a shorter or a 
longer time, the nucleus is a glossy hyaline body with considerable re- 
fractive power and no discoverable structure. 
But directly a change is about to ensue the nucleus puts on the first 
evidence of it. The cyclic change of these unicellular organisms is, that 
after growth from the germ or egg emitted from a maternal sac, and 
when maturity is attained, the cells go through rapid and successive fis- 
sion. Their division into two or more in every case is complex, inso- 
much that, however complicated the flagella of the organism may be, the 
division is so effected as to produce for each divided part the flagella 
possessed by the original undivided form, and so with the nucleus. 
Following upon this, after a long series of fissions extending over 
many hours, the final links unite with other ordinary forms, the proto- 
plasm of each melting into the other and producing a sac in which the 
genetic seed arises, from which a new generation grows. 
Now the added point of great moment is that I can now — previous 
to the first fission in a new generation — discover the initiation of this 
act in the nucleus. In fact a powerful change takes place. The 
hyaline particle becomes turbid, as I now know, with structure ; this 
structure divides, and this initiates the division of the nucleus. Upon 
this follows the division of the whole organism. 
This takes place in every fission. 
But quite another change comes over the nucleus of the last link in 
a chain of fissions. Instead of becoming semi-opaque with structure, it 
becomes opaque by what, to our present resources, is a homogeneous 
milkiness, and greatly enlarges. 
