268 Proceedings of the Royal Physical Society. 
pronucleus, we do not see any warrant for the assumption. 
We know nothing as to the qualities of the minute quantity 
of cytoplasm extruded along with the nuclei. (2) We do 
not regard the sperm as a concentrated mass of waste- 
products, but believe it to be the bearer of paternal hereditary 
characters plus a certain amount of living matter such that 
itacts as a physiological stimulus to the ovum. (3) As the 
sperm is a unit with a minimum store of potential energy, 
with a habit of great activity, we conceive it possible that 
the living matter which it brings to the ovum is very 
different from that characteristic of the ovum which is rich 
in accumulated potential energy. (4) Although the ovum 
has ceased to accumulate potential energy when it is mature, 
and is living on its own resources, we believe that its 
characteristic vital ratio = is, like that of the female organ- 
= of the sperm and of the male 
organism. (5) We do not believe that “anastates” and 
“katastates” are mythical entities, but as much realities 
as the “temperament” and “constitution” of which Hartog 
speaks. We believe that they are chemical substances char- 
acteristic of the metabolism of ovum and sperm respectively, 
corresponding to the physiological contrast between them. 
In short, we believe that the renewal of the firm has a 
chemical basis. Yet Hartog’s criticism is salutary, for 
definite statements should not be hazarded where ignorance 
is still supreme. 
We have more satisfaction in outlining Hartog’s concep- 
tion of the origin of sex. He finds a clue in the history of 
the Volvocine Pandorina: its gametes are of three sizes— 
microgametes (a), mesogametes (b), and megagametes (c); the 
possible unions (all exogamous) are said to be a+a, 0+48, 
(isogamous); a+b,a+c, and b+e (anisogamous); c+c does 
not occur, “as if, concurrent with its enlargement, the 
form ¢ had become too inert to form isogamous unions.” 
“We may conceive that, the gametogenic divisions in a 
species being inconstant, broods of gametes would be formed, 
whose size was inversely proportional to the number of the 
ism, greater than the. ratio 
