34 THE SAPROLEGNIACEAE 



spherical with a short neck when apical, but at times oval to pear-shaped, 

 and when intercalary oblong to flask or spindle-shaped with long necks; 

 33-92^1 in diameter, most about 55-6511.; at maturity with moderately 

 thick walls that appear unpitted except beneath each antheridium, 

 where there is always a distinct circular pit (when young, just before 

 the formation of the egg initials, the oogonia present a spotted appear- 

 ance from the arrangement of droplets of oil in the protoplasm, as is 

 usual in the family). Eggs 1-20, mostly 4-6, quite variable in size 

 even in the same oogonium, i7-38[x in diameter (not rarely some very 

 small ones as little as i3tA thick), most about 2i-27fjL, centric. 



Antheridial branches quite slender and soon becoming very in- 

 conspicuous, arising from any of the main branches, usually from the 

 proximal half, and running to oogonia on other branches than the one 

 from which they arise (diclinous) ; oogonial branches often give rise 

 to antheridial branches lower down. Antheridia cylindrical or tuber- 

 ous, present on all oogonia, usually several to many, when young well 

 filled with protoplasm, in age apparently empty; antheridial tubes formed 

 in most cases and remaining visible for some time after the eggs are 

 formed. Gemmae more or less numerous or rather few, usually spherical, 

 sometimes pear-shaped or tuberous and of other shapes, usually in short 

 or long chains, easily becoming sporangia on change of conditions, empty- 

 ing by a proliferating tube. Often there may be several proliferation 

 tubes, but only one opens for the escape of the spores. 



Rare, and found only three times, twice in Chapel Hill collections, 

 from Arboretum branch (No. 12 of January 30, 1913), and from a marshy 

 sink opposite the cemetery (No. 2 of January 2, 1917), and once in Wil- 

 mington, N. C, in a ditch at the golf links, this last a form with some- 

 what larger oogonia and more numerous eggs. No. 12 of January 30, 

 1913, was cultivated for about four months from a single spore and 

 No. 2 of January 2, 191 7, was cultivated for a year and a half, part of 

 the time from a single spore. The species is distinguished by its char- 

 acteristic sporangia, two or more sizes of spores, and diclinous anther- 

 idia on every oogonium. 



The frequent appearance of two or three sizes of spores recalls S. 

 anisospora, and we have become convinced that our plant is that species. 

 But for the centric eggs there is no great difference to be noted in de- 

 Bary's description.* In fact, the small oogonia with unpitted walls, 

 the small number of eggs, the numerous and conspicuous diclinous an- 

 theridia on each oogonium, and the very variable spores form so striking 

 a set of similar characters, particularly as in this group of characters 

 both species are well separated from all others, that one is inclined to sus- 

 pect that deBary, who rarely made a mistake, was in this case wrong in 



*DeBary's description of the oogonia as club-pear-shaped is evidently a distinct ex- 

 aggeration of the tendency to that shape. His figures show oogonia that are spherical or 

 slightly pear-shaped. 



