REPRODUCTION IN LOWER PLANT LIFE. 111 
And here I cannot avoid the temptation of travelling 
somewhat beyond the limits to which I originally proposed 
to confine myself in the present paper, and to refer for a 
short space to phenomena observed in the animal kingdom, 
specially to the remarkable observations of Professor 
Weismann, and the brilliant deductions which he has 
drawn from them, contained in his recently published 
volume of Essays, and in a most interesting article in 
“Nature” for Feb. 6th. Into the wide-reaching problems 
discussed by Weismann it is entirely beyond my province 
and beyond my competence to enter. I wish merely to 
call attention to one of his conclusions:—that the 
old idea of an essential difference, at all events of an 
opposition, between male and female elements, between 
so-called “‘ sperm-cells”’ and ‘‘ germ-cells”’, must be aban- 
doned; that ‘‘ they are essentially alike, and differ only so 
far as one individual differs from another of the same 
species’’; and that “‘ fertilisation is no process of rejuven- 
escence, but merely a union of the hereditary tendencies 
of two individuals.” This view, the correctness of which 
I do not propose to discuss, he supports from the results 
of experiments which he regards as demonstrating the 
extraordinary fact that, even in animals as high in the 
scale as the Batrachia, the ‘‘sperm-nucleus”’ can be made 
to play the part of “‘ovum-nucleus”’, and wee versa; it being 
possible to produce a free-swimming larva in the form- 
germ-nucleus”’ has taken no part. 
(a9 
ation of which a 
These remarkable facts may be regarded as complemen- 
tary to the much more frequent phenomenon of partheno- 
genesis, familiar to all students both of animal and 
vegetable biology. 
Whether or not we adopt Weismann’s view with regard 
to the higher developments of the process of fertilisation, 
I think the facts I have brought before you lead beyond 
