1 68 Trow . — Observations on the Biology and 
not take place in another species, any more than the demon- 
stration of four chromosomes in the nucleus of one species 
precludes the occurrence of one, two, eight, or any other 
number in the nuclei of some other species. Such evidence 
as that adduced by Hartog can be explained easily enough 
without reference to debatable theories. 
May I suggest to those who believe in the disappearance of 
the supernumerary nuclei in the oogonium by nuclear fusions, 
that they should demonstrate to us the last stages in the 
process ? It ought not to be impossible, it ought not to be 
difficult, to show naked oospheres with two or more nuclei. 
It would be especially convincing if preparations of the stage 
known as ‘ balling ’ could be shown with the nuclei . It is at 
this stage, where the degenerate nuclei are almost or quite 
digested according to my view, and the single surviving 
nucleus is in the last stages of anaphasis but without a 
nucleolus, that the chief difficulties are met with. According 
to the views of Hartog and others such stages should be 
exceedingly easy to demonstrate, for the nuclei as they fuse 
ought surely to get bigger and bigger and more and more 
prominent. Until figures are forthcoming of this critical 
stage in the development of the oospheres it will be wise 
to ignore all criticisms as to the improbability of fertilization 
and the probability of nuclear fusions in the oogonium. 
Significance of the Nuclear Divisions 
IN THE GAMETANCxIA. 
A consideration of the nuclear divisions in the gametangia 
of species of Saprolegnia led me three years ago to a view of 
some theoretical interest which I expressed as follows : — ‘ The 
sporophyte-generation of the higher plants probably owes its 
origin to the fusion of gametes whose nuclei did not undergo 
a reducing division. The doubling of the chromosomes acted 
as a stimulus to spore-formation and involved a halving of the 
chromosomes in the return to the undoubled condition of 
the nuclei in the gametophyte-generation.’ The return to the 
original condition may under such circumstances be very well 
