164 Trow. — Observations on the Biology and 
the inference that these two nuclei originated in the oogonium 
appears to have been based entirely upon hasty conclusions 
as to the impossibility of fertilization taking place. Humphrey’s 
methods, moreover, were scarcely adapted to elucidate the 
difficult question of fertilization ; and as he neither examined 
oogonia in the stage of balling , nor naked oospheres, a correct 
interpretation of the complicated phenomena which take 
place here was obviously out of the question. We need not 
then consider further his view, unsupported as it is by a 
single figure, that the supernumerary nuclei are got rid of 
by successive fusions. As, however, the nuclei in the 
oospores are easily identified, and they appear to agree 
closely with those of the var. cambrica , and especially in 
view of the evidence brought forward in this paper, it may 
fairly be concluded that fertilization takes place in Achlya 
americana. This being so, I venture to draw special attention 
to the fact that fertilization is now known to take place in 
four distinct forms of Saprolegnieae ; viz. Saprolegnia diclina , 
A. mixta , Achlya americana , and A . americana var. cambrica. 
Hartog’s views deserve much closer attention, for he devoted 
himself almost exclusively to cytological studies. 
To avoid tedious recapitulation of trivial points I will direct 
attention to those features alone which lead to real differences 
of opinion. It will be necessary in this case to consider the 
text of Hartog’s communication separately from the figures 
which illustrate it. 
As I have previously stated, the textual statements of Prof. 
Hartog do not differ greatly from my own. Bearing in 
mind that we were working probably with different material 
and certainly using widely different methods, the extent 
of the agreement, as to fact, is astonishing. Indeed, had 
Hartog been able to follow the division of the nucleus in the 
oogonium (as he did in the antheridium) and to recognize 
the nucleus in the naked oospheres, he would probably have 
never promulgated his remarkable theory of the ‘ multiple 
endogamous union of potential gametes.’ It is so difficult 
to find a reason for a wholesale fusion preceded by an indirect 
