ORDER SAPROLEGNIALES 117 



The antherid may subtend the oogone, directly, or arise on a short stalk 

 from immediately below it. No conjugation tube seems to be produced. 

 Germination of the oospore is by means of one or two germ tubes. 



In ApodachlyeUa zoosporangia have not been observed. The spherical 

 or pyriform oogones contain 2 to 12, more often 4 to 7 eggs, which become 

 thick-walled oospores without surrounding periplasm. The slender con- 

 stricted antheridial branches, 2 or 3 in number, arise from the segment 

 below the oogone. A conjugation tube is produced by each functioning 

 antherid. 



Family Rhipidiaceae. In this family the mycelium is provided with 

 well-developed holdfast hyphae bearing a more or less thickened, some- 

 times even spherical, basal segment from whose upper portion arise 

 slender, often constricted, hyphae terminated by zoosporangia or by the 

 sexual organs, or both may arise directly from the basal segment 

 (MindenieHa). Only zoospores of the secondary type are produced. The 

 oogone contains a single egg surrounded by periplasm which in one genus 

 {Araiospora) forms a cellular layer closely investing the oospore. 



Sapromyces, with two or more species, grows on sticks, etc., in water, 

 being attached by its rather few rhizoids. The upright main axis is not 

 much thickened in comparison to the several slender, constricted branches 

 that arise at its apex. These bear at their apices one to several obovoid, 

 clavate, or cylindrical zoosporangia which give rise to numerous biflagel- 

 late, kidney-shaped zoospores which escape directly or into an evanescent 

 vesicle. Possibly due to sympodial growth some of the zoosporangia may 

 appear to be lateral. On the same branches with the zoosporangia or on 

 separate branches the oogones and antherids arise. These also may be in 

 terminal clusters of two or more, or single, or may appear to be lateral. 

 The obovoid oogones contain each a single egg with abundant periplasm. 

 The clavate antherid is borne on a slender, sometimes coiled hypha arising 

 from just below the point of attachment of the oogone. It becomes 

 attached to the oogone at the apex. 



Rhipidium, with four species, consists of a thick, more or less cylindri- 

 cal body with numerous rhizoids, growing on fruits, twigs, etc., in water. 

 At its top it gives off slender branches which are constricted here and 

 there. Terminally on these slender branches arise the ovoid zoosporangia 

 which may later appear lateral on account of the sympodial mode of 

 growth of the hypha. The protoplasmic contents of the zoosporangium 

 divide into numerous zoospores which push out into a cylindrical vesicle. 

 Upon the rupture of the latter the biflagellate, kidney-shaped zoospores 

 escape. The oogones are also terminal on slender branches and contain 

 each a single egg surrounded by a layer of periplasm. The antherid may 

 arise on a slender branch just below the oogone or on a longer branch 

 from another plant. It attaches itself to the basal portion of the oogone. 



