ING. tT.) REGENERATIVE ENERGY. 35 
the protoplasm a passive mass, moved at the expense of nuclear 
energy alone, or has it motor energy of its own? In the latter 
case, are the conditions necessary to action supplied by the 
nuclei or by the protoplasm, or by both? Although we are yet 
a long way from a solution of these questions, it may be possi- 
ble to show that the protoplasm is an active rather than a pas- 
sive factor in the movements we are considering. Any view 
which represents the germinal protoplasm as a passive body, 
moving only as it is impelled by nuclear forces, appears to me 
irreconcilable with the following facts : — 
1. In most meroblastic vertebrate ova (including those of 
many teleostei), the germinal disc is already formed before fec- 
undation takes place. The ma/e pronucleus cannot therefore 
be a necessary factor in the formation of this disc. 
2. In many pelagic fish ova, where the disc forms after fecun- 
dation, the polar amphiaster is formed before polar concentra- 
tion begins. The cause of concentration cannot therefore, in 
this case, be referred to the centrifugal movement of the 
germinal vesicle, nor to any changes which this body undergoes 
prior to the formation of the polar amphiaster. 
If this conclusion holds equally in the first class of eggs, we 
are fully warranted+in affirming that the germinal disc forms 
independently, not only of the male pronucleus, but also of the 
germinal vesicle and its derivatives, since in these eggs the disc 
is formed before fecundation and before the polar amphiaster 
divides. 
The validity of these conclusions may be disputed by those 
who hold with Weismann (No. 6, pp. 90-122) that the two pronu- 
clei are identical in their molecular structure, and that both act 
alike upon the protoplasm, but in proportion to their mass. It 
might be argued that a definite guantity of karyoplasm (‘ Keim- 
plasm’) is requisite in order to concentrate the protoplasm in 
the form of a polar disc. If the mass of the germinal vesicle, 
or of its pronuclear elements, be large enough, it would form a 
germinal disc without the aid of the male pronucleus; if it fall 
short of the requisite mass-measure, it would have to be reinforced 
by the male pronucleus before it could accomplish the work. It 
will be time to accept this view when it has been shown that 
there ave such quantitative relations as the theory postulates. 
Such an explanation of the disc-formation would take no account 
