ACHLYA AND SAPROLEGNIA. IQj 



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 oospore 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 SaprolegniaceaB. 



From the foregoing it is clear that certain similarities exist between 

 these genera and such forms as Albugo. The development of the 

 sexual organs themselves, and the earlier conduct of the numerous 

 nuclei which enter the young sexual organs from the parent hyphae, 

 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. 



