1885.] Zoology. 1225 
two, or three planes, and give rise accordingly to very different 
aggregates, 
As to cell growth, the size will depend directly on it; but like 
multiplication, growth may affect some cells and not others; 
again, like multiplication, cell growth may take place in one, two, 
or three dimensions. 
W now readily see that the guantity and quality of cell 
multiplication and cell growth, according to a specific type of com- 
bination for the different organs and thus for the whole organism, 
builds up the individual with its specific characters, 
ow, the nucleus governs cell multiplication. (1) Division of 
the nucleus leads in cell division. (The author here shows that 
certain apparent exceptions are not really so.) (2) The position 
of the nuclear spindle determines the plane of division. 
The nucleus also governs cell growth. ` 
(1) Young and active cells have conspicuous nuclei, while cells 
that have done their work are without them. (2) The size of the 
nucleus increases as the cell increases (cf. Actinospherium). 
The nucleus in large cells may separate into many parts so that 
every portion of protoplasm shall have a nucleus to preside in it. 
In protozoa these nuclei fuse again before division of the cell, 
while cases where the mass breaks up without this union are 
where the nuclei have become independent cells, viz: swarm 
spores. (3) Artificial division of Protozoa, shows that pieces 
without a nucleus do not grow. (4) Free cell formation may be 
considered as due to the fusion of minute nuclei (vid. Berthold, 
Mitth. der Zool. Stat. Neapel, ii, p. 78) and around the nucleus 
thus arising a cell is formed. (5) As several of Haeckel’s innu- 
cleate monera have shown nuclei, when treated with appropriate 
reagents, Kolliker expects that all will do so when investigated 
by the methods of an advanced staining technique. (6) The 
activity of the nucleus is shown by the rays that stream from it 
in the protoplasm, and by the active manner in which it reacts 
towards stains. 
From this we conclude, that the nucleus has great and con- 
trolling significance for the cell, being in active relation to the 
protoplasm.! Some authors have given it the function of manu- 
facturing albumen, chlorophyll, etc. The structure of the cell, in 
fact its life history, ts conceived to depen on the nucleus, whose 
idioplasm has a minute structure of a definite type for each species ; 
and on this structure will depend the method of its work and 
how it shall react towards external influences. Modifying forces 
trix of achromatin; and that modern cytologists have generally applied the 
pert ereid, to only the chromatic portion, wholly ignoring the achromatic.— Y. W. 
