278 Proceedings of the Royal Physical Society. 
if the idants be the material basis of hereditary qualities 
(which seems to us a very natural assumption), the possibility 
is by no means excluded, that associated substances may have 
a dynamic influence in fertilisation. We acknowledge, of 
course, that Weismann is justified in making out the strongest 
possible case for the unique importance of the chromatin 
rods: it seems to us that we are also justified in maintaining 
that the cytoplasm has some claims to be considered. 
(>) As we have seen, Weismann attaches great importance 
to the “reducing divisions” of maturation, which remove 
half a set of hereditary predispositions and permit of the 
arrangement of the remainder in fresh combinations. It 
cannot be denied that this speculation is exceedingly 
ingenious ; if the facts are really as Weismann believes, an 
important contribution has been made to our knowledge of 
the morphological aspect of variation. But it must be 
noticed (1) that the ingenious interpretation owes its value 
to an antecedent hypothesis as to the nature and arrange- 
ment of the ancestral plasms or “ids” within the idants,— 
an hypothesis which may or may not be true; and (2) that 
it is quite possible that the processes of sperm- and ovum- 
maturation in Ascaris megalocephala, var. bivalens, may not 
be typical. Weismann considers this last objection with 
the same carefulness which, Darwin-like, he displays through- 
out in anticipating difficulties, but whether his clever har- 
monising of Henking’s somewhat divergent observations on 
Pyrrhocoris will stand remains to be seen. The homology 
between the formation of spermatozoa and ova, between the 
two divisions of the sperm-mother-cell and the formation of 
two polar bodies, has been traced by Hertwig in Ascaris, by | 
Platner in butterfly and snail, and to some extent by 
Flemming in the salamander; but it is a matter of opinion 
whether “we may well believe that we are dealing with 
a process of general significance, and one which is repeated 
during the formation of the sexual cells of, at any rate, all 
the higher Metazoa, in essentially the same way.” It seems 
to us that there remain at present a large number of described 
cases of spermatogenesis in which a double “reducing 
