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Transactions of the Society. 
or accumulation of energy within the nucleus, as far as we 
know. Therefore both raw material for structural purposes within 
the nucleus, and the energy for the vital activities must be supplied 
during early stages of growth by the cytoplasm. 
(iii.) That the chromosomes as the physical bases of heredity, 
during development must be continually exerting their controlling 
influence upon the cytoplasm ; this they probably do by a kind of 
enzyme action. The weakness of binuclear theories previously 
referred to is, that they split the functions of the nucleus into two 
separate groups — the one nutritional, the other hereditary — whereas 
the two are really one. The various hereditary characteristics are 
probably due to the type and nature of the metabolic processes 
existing in the cells of the developing embryo ; the varying nature 
of the chromosome influence upon the cytoplasm producing the 
different hereditary characteristics. Whether this aspect of the 
subject is admitted or not, the fact that there must be an extrusion 
of substances from the nucleus into the cytoplasm is undeniable. 
The only types of extrusion from the nucleus into the cytoplasm 
so far described are, firstly, chromatin extrusions of which we have 
practically no undisputed evidence, and, secondly, nucleolar 
extrusions. The question arises as to whether nucleolar extrusions 
represent substances elaborated by the chromosomes for the 
purpose of exerting formative influences ; or, in the language of 
physiology, are chromosomes a type of pro-enzyme, and nucleolar 
extrusions enzymes ? I do not wish to do more than state the 
problem here ; nothing but much further research can solve it. 
It is necessary to point out however the conclusions of workers 
in experimental embryology, that “ the larger characters, those of 
the phylum class, order and family to which the animal belong, are 
carried by the cytoplasm ” ; and that the smaller characters, generic, 
specific, variate and individual, are transmitted “through the male 
and female pronuclei (ibid. Jenkinson). Also at the same time 
the cytoplasm is during pre-maturation stages, indebted to the 
nucleus for certain elements in its structure ” (29). 
In connexion with the intaking of material by the nucleus 
from the cytoplasm, Montgomery (4-2) considered the nucleolus 
played an important part. He pointed out that in certain cases 
the nucleolus first makes its appearance as a small body attached 
to the nuclear membrane. 
Other workers have observed basophil staining substances in 
the region of the nucleus, which they interpret as substances being 
absorbed by the nucleus. Nakahara (46), in a recent paper, describes 
such an occurrence in the oocyte of the stone-fly, Perla. At the 
time when the basophil substance appears, the nucleus is relatively 
small, but at later stages, when the same substance can no longer 
be seen in the cytoplasm, the nucleus is much larger and contains 
large nucleoli. His explanation of the process is that the nucleolus 
