1 8 THE SAPROLEGNIACEAE 



smooth or with a few bkmt papillae. Antheridia short and thick, typi- 

 cally androgynous from the close neighborhood of the oogonia. Eggs 

 one or few, eccentric, with a lunate cap of droplets on one side in 

 P. cymosa; structure doubtful in P. Htimphreyana. 



Key to the Species 

 Sporangia globular or clavate; oogonia sometimes with a few blunt outgrowths; egg single, 



14. 8-18. 5m thick P. cymosa (i) 



Sporangia occasionally elongated; oogonia always smooth; eggs generally one, occasionally 



2, and very rarely 4, about 30^ thick P. Humphreyana (2) 



I. Pythiopsis cymosa deBary. Bot. Zeit. 46: 631, pi. 9, fig. i. il 



Plate I 

 Hyphae slender, 14.8-22.5jj. in diameter at base, short or moder- 

 ately long. Sporangia globular or clavate. Spores 8.6-io.8iJ., most 

 about 9;j.; monoplanetic. Oogonia plentifully formed in old cultures, 

 spherical to oblong or pear-shaped, unpitted, smooth, or sometimes 

 with a few blunt outgrowths, terminal or rarely intercalary, 18-30^. 

 in diameter, a few smaller. Eggs mostly 14.8-18.5:0. in diameter, but 

 sometimes up to 24(ji, single (Humphrey says rarely two to an oogonium) , 

 eccentric, as described above. Antheridial branches short or none, usually 

 arising from just below the basal walls of the oogonia, rarely diclinous. 

 Antheridia one or two to each oogonium, clavate; antheridial tubes pres- 

 ent, at times growing up through the basal wall of the oogonium. 

 Gemmae of more or less globular or ovoid shape are formed in quantity 

 and are often arranged in chains. After a rest these also form zoospores. 



Rather rare in springs and branches, as Terra Cotta spring, branch 

 in Pritchard 's pasture. Glen Burnie meadow, etc. Collected seven times, 

 and all in winter. Heretofore reported from America only by Humphrey, 

 from Amherst, Mass. See his plate 17, figs. 60-68; also Minden ('12), 

 figs. 3a, 3b on p. 556. 



The species may be easily distinguished from P. Humphreyana 

 by smaller oogonia with sometimes a few blunt outgrowths, smaller 

 eggs, smaller sporangia, presence of basal antheridia, and absence of 

 elongated forms of sporangia. See Mycologia 6: 285, pi. 147, 1914, 

 from which the figures and most of the following notes are taken : 



The sporangia, oogonia and antheridia are well shown by deBary 

 and Humphrey, but variations occur that were not observed by them. 

 The antheridial cells, as formed in about one-half the oogonia, are unique 

 in position. They arise by the enlargement of the hypha immediately 

 below the oogonium and the growth of this segment along the base of 

 the oogonium for a short distance. A tube is formed near the septum 

 and enters to the egg. As the antheridial cell is in close contact with 

 the oogonial wall from the septum out, the position of the septum be- 



