2 o 8 Farmer and Digby.—On the Cytological Features exhibited by 
so obvious during the progress of mitosis, a change which has often been 
interpreted as indicating alteration in osmotic relations, or, less precisely, 
has been ascribed to growth changes, seems to us to find a less strained 
explanation when regarded as due to change of electrical state than in 
any other way. It has been shown that the size of the nucleus may 
alter during the prophase of division, and that this may be correlated 
with the changes in the chromatin. Further, that the ‘ growth ’ is not 
regular, but may oscillate in the plus and minus directions. And it cannot 
escape notice that the periods of maximal size coincide with the spreading 
out of the chromatin beneath the nuclear wall, that is, with conditions 
that tend to lower the surface tension of the membrane, or even to 
bring about its disappearance altogether, by resolving the coagulated state 
to which it almost certainly owes its existence. The time has admittedly 
not yet arrived when it will be possible to give an explanation of these 
cellular changes that will prove completely satisfactory from a physical 
point of view. We have still much to learn concerning the modifications 
imposed by the physical and other properties of the colloids 1 in which 
the chemical disturbances that are bound up with the changes of form 
and with the genesis of structures such as those we have been considering 
are taking place. For example, as Hartog pointed out, the lines of force 
in a magnetic field , 2 although they may be mapped out by the arrange¬ 
ment of those cell constituents which, as he says, are more ‘permeable', 
may be themselves abolished or otherwise modified, without a simul¬ 
taneous effect becoming at once manifest in the ‘ chains ’ formed of 
material particles which are relatively immobile, and tend to retain any 
particular arrangement (in this case approximately that of lines of force) 
in which they have been cast until, by the action of other forces, they are 
compelled to assume new positions. 
If we now turn our attention to the behaviour of the nucleus, we find 
the infertility of the varietal form as well as of the sport to be inti¬ 
mately related to degenerative changes in the nucleus. We have seen how 
degeneration may set in at an early stage in the history of the development 
of the sporangium, and that the lethal processes are first visible in the 
nucleus. The cytoplasm also is very characteristically altered, and gives 
the impression of being starved. The same is true of the separated spore 
mother-cells, except that in them the starvation in the cytoplasm is more 
definite, doubtless owing to the poor nutrition consequent on the failure of 
the tapetum to develop properly. It is at any rate quite clear that the 
normal relations between the cytoplasm and the nucleus have become 
1 e. g. the adsorption of ions, dissociation or association products, on the colloidal surfaces. 
- It may be as well to point out that there can be no question of the existence of magnetic forces 
in the cell. The problem is one of electrostatics, and Hartog showed he was iully aware of this; 
cf. his paper on ‘ The dual force of the dividing cell ’ in Science Progress, 1907. 
