326 



Mycologia 



members of the racemosa group the antheridial tranches, when 

 present, originate just below the oogonium. In A. glomerata 

 they do not thus originate. This distinction with the usually 

 bent and twisted branching habit of the oogonial hyphae separates 

 the species sharply from any of the racemosa group. As already 

 mentioned, the oogonia are sometimes borne singly on the ends 

 of simple branches, especially near the tips of the main hyphae, 

 but in such cases these branches are much more delicate and 

 longer in proportion to the oogonia than is generally the case in 

 any member of the racemosa group. 



The fruiting branches are so abundant and many of them are 

 so elongated and extensively branched that the cultures take on 

 a whitish, cottony appearance except near the periphery, which 

 is usually without branches. In extreme cases this effect is so 

 pronounced that the culture may be compared in appearance to 

 a rug with a fringe. This reminds us of the " woolly snow-white 

 turf " produced by deBary's Achlya spinosa,^ which species, while 

 not in the close family circle of the racemosa group, shows its 

 relation to them by its spiny oogonia with generally one egg, and 

 by the origin and shape of the antheridia. 



So far as the sexual organs are concerned, there is a remark- 

 ably close resemblance between Achlya glomerata and Saprolegnia 

 asterophora deBary.^ As in most species of Achlya, the spores 

 sometimes remain in the sporangium and sprout there (fig. 7).* 



Chapel Hill, North Carolina. 



Explanation of Plate LXXIX 



Fig. I. Part of filament from an old culture, showing segmentation into 

 chlam.ydospores. Part of one long cell is omitted. The contorted tip cell is 

 almost empty. X 185. 



Fig. 2. A group of sporangia in different stages. X 125. 

 Fig. 3. A simple oogonial filament with one oogonium. X 335- 

 Fig. 4. A branched oogonial filament with two oogonia. X 335- 

 Fig. 5. A more complex group of oogonia, not all shown. One is inter- 

 calary. X 335- 



Fig. 6. A characteristic group of oogonia with antheridia. The proto- 

 plasmic contents are shown only in part. X 335- 



Fig. 7. A sporangium in which the spores became encysted and sprouted 

 in position. X 335- 



^Botanische Zeitung 46: 647. 1888. 



^ See Beitr. zur Morph. und Phys. der Pilze, IV. Reihe, 1881. 

 *See article by the author in Bot. Gaz. 50: 381. 1910. 



