ACHLYA AND SAPROLEGNIA. 107 
kinetically, and the process is repeated until by the time a germ-tube 
is evident, or even before, about twenty nuclei are present. 
It may be objected that Trow’s evidence of the passage of the sperm 
nucleus into the egg is insufficient, and that the two nuclei seen in the 
young odspore may have been derived from a division of the unfecun- 
dated egg-nucleus. While such objections have but little weight, yet 
we must admit that the possibility of their truth is not excluded. For 
many of us Trow’s observations will have a probability bordering on 
certainty. Although the conclusions of Trow require confirmation, 
yet I think it can be fairly said, and that too with all due respect for 
the ability and skill of De Bary and others whose observations tend to 
confirm his view, that Trow has furnished the strongest evidence that 
has thus far been brought forward in support of the existence of 
sexuality in certain species of the Saprolegniacez. 
From the foregoing it is clear that certain similarities exist between 
these genera and such forms as Aléugo. The development of the 
sexual organs themselves, and the earlier conduct of the numerous 
nuclei which enter the young sexual organs from the parent hyphe, 
are quite parallel. The great difference lies in the differentiation of 
the egg-cells. In Saprolegnia and Achlya we have developed, as a 
rule, several eggs, and there is no trace of periplasm. The super- 
numerary nuclei disorganize before the egg-cells are differentiated. In 
Albugo and closely related genera, the supernumerary nuclei, if we 
may be permitted to speak of those of the periplasm as such, having 
different and additional functions, disappear later. 
