Observations on Saprolegniea. 137 



about .01 mm. A short specimen, magnified 120 times, is 

 shown in PI. VI., Fig. 2; its base was completely separated 

 from the matrix on which it grew, so that its branching 

 character could be readily seen, and in many other speci- 

 mens this peculiar root-like branch ng was very evident. 

 The same character also holds in the parthenogenetic forms, 

 and in all, the base was perfectly clear. In the Saproles^nia, 

 however, this dendroid character is not always present, for I 

 have frequently seen the sporangium-bearing hyphae spring 

 from a thick net-work of mycelium. I think that consider- 

 able weight should be placed upon this character, for it is 

 quite constant and very noticeable in old specimens. 



The parthenogenetic form is largely similar to that already 

 described under Saprolegnia sp.: the aggregation of the gran- 

 ules and segmentation of the protoplasmic contents took 

 place in the same way, while the chief difference lies in the 

 fact that in Achlya the zoospores, after escaping from the 

 sporangium, remained clustered around the opening. 



The distinction upon which Karl Lindstedt (4) places the 

 most weight is that the zoospores of Achlya undergo the 

 second change which I have described, while those of the 

 Saprolegnia do not. This division is faulty, as shown in the 

 case of Saprolegnia, where an occasional sporangium pro- 

 duced zoospores that underwent this rejuvinescence, although, 

 as a rule, it did not take place. So in the genus Ac/ilya, 

 although germination without transformation is the exception, 

 it does occur (PI. VII., Fig. 3). 



Taking up now the sexual generation, we find a very complete 

 arrangement for the production of fertilized fruit. From the 

 filaments are developed lateral, spherical bodies, the contents 

 of which segment into spherical masses that are fertilized 

 through the action of lateral branches (PI. VI., Fig. 2). 



In the development of this organ, there is first produced on 

 the side of the filament a small swelling, having much the ap- 

 pearance of a lateral branch. As growth proceeds it increases 

 but slightly in breadth towards the apex, until nearly the full 

 length is reached, up to which time it is nearly as clear as the 

 filament from which its takes its rise. At this stage, four hours 

 from the filament, the granules become more dense, giving a 

 dark center to the young oogonium, and as the organ swells 

 more at the tip the granules increase, rendering the whole in- 



