140 American Quarterly Microscopical Journal. 



These lateral, spherical oogonia are not the only forms 

 produced, for very frequently in this species there were also 

 developed cylindrical, interfilamental forms (PI. VI., Fig. 11), 

 which bear a single row of from two to seven gonospheres. I have 

 never seen them terminal, though they always precede the lat- 

 eral forms borne on the same filament. The gonospheres are 

 of the same size and formed in the same manner as in the 

 other case, but frequently occur oblong instead of round. I 

 could rarely determine the presence of an antheridium, but 

 when seen it extended only to the lower portion of the 

 sac, so that the spermatozoids must pass free into the in- 

 terior to insure perfect fertilization. 



In October, 1877, a very similar form was found upon a leaf- 

 petiole of the sycamore {Platanus occidenfalis, £.), differing chief- 

 ly from the preceding in having oogonia of quite variable 

 sizes, some being as large as forms growing on the pine twigs, 

 while others contained but a single gonosphere each, and were 

 then only large enough to hold it, also in being generally of a 

 deep brown color. 



This Achlya is, in many respects, similar to A. racemosa, Hild. 

 (3), yet there are many differences worthy of notice, although 

 they may not be of sufficient importance to merit for it a 

 specific name. The plant that I have described is much more 

 simple, being slightly branched, when branched at all; the 

 sporangia are always terminal, presenting no raceme-like char- 

 acter whatever; the oogonia are rarely terminal, and the 

 antheridia empty their contents, as a rule, directly into the 

 oogonium;* also the frequent production of cylindrical, inter- 

 filamental oogonia. Achlya lignicola, Hild. (3), which presents 

 about as prominent differing characters as these, is considered 

 by later authorities (2) (6) to be only a variety of A. raccnwsa; 

 and so in this case I shall designate the form dealt with by 

 Achlya racemosa, var., suggesting, at the same time, that Achlya 

 variabilis would be a much more appropriate name for the 

 three combined. 



In September, 1878, I found a very branching form of Achlya 

 growing upon a dead frog which had been trapped in a spring; 

 the water was very cold and fresh, conditions most favorable for 

 the growth of Saprolegnieae. In this case the filament reached 



"I have since seen an antheridium just before, and again just after, the spernr.atozoids had passed 

 out, and no tube was formed. 



