I40 THE SAPROLEGNIACEAE 



ually towards the apices, where they rather suddenly narrow to fairly 

 sharp points. 



"Sporangia terminal, cylindrical, scarcely thicker than the sup- 

 porting hyphae, of a length generally' varying from 250:ji to 3681A and of 

 a breadth varying from 39ijl to ~2\}. (average of six measurements — ■ 

 length 3i5[ji., breadth 561J.) ; sometimes very small, producing in extreme 

 cases no more than three or four zoospores; generally developed in the 

 typical cymose order, the main axis, however, frequently septate behind 

 the oldest sporangium, each segment thus formed, of which there may be as 

 many as ten, developing a short branch, the segment and branch together 

 constituting a sporangium. 



"Spores very numerous, averaging I3!jl in diameter, generally en- 

 cysting at the mouth of the sporangium, occasionally, however, in^ 

 side it. 



"Oogonia, on short unbranched stalks, which are about as long 

 as the diameter of the oogonium, and of an average breadth of lOtJ.; at 

 first developed regularly in racemose order on the main hyphae; gener- 

 ally terminal and spherical, but not infrequently intercalary and barrel- 

 shaped; of a diameter 31 ;j, to 8511. (average of twelve measurements 60(a), 

 with a thick, pitted, yellowish smooth wall; frequently, however, provided 

 ivith blunt spines, ivhich may exceptionally even reach the length of 2^11, 

 and are due to outgrowths through the pits. 



"Antheridia, always present under natural conditions, /ew in num- 

 ber, produced on branched antheridial filaments of a diameter of 6.^\x, 

 which arise from the main hyphae side by side with the oogonial branches, 

 or, as observed in a very few cases only, from the stalk of the oogonium ; 

 of very variable shape, but generally long and curved, and closely applied 

 throughout to the surface of the oogonium, or opposite the pits only by 

 means of outgrowths from the under surface; sometimes septate; of a 

 maximum length of 651^ and maximum breadth of 7;j.; emitting from 

 points in contact with the pits one or more branched or unbranched 

 fertilization-tubes of a diameter of 41X. 



"Oospores, one to twenty or more, mostly from three to eight (aver- 

 age of twelve cases six); spherical, with a smooth, very thick two-layered 

 wall; eccentric, of a diameter of 23^ to 26^, and having an oil-globule of 

 a diameter of 15a; germinating at once, and producing a long, thin, 

 branched hypha, or one or more small sporangia, or passing into a rest- 

 ing condition and remaining capable of germination for at least four 

 months." 



A little further on (p. 137) Trow says: 



"The specific type as described and figured by Humphrey has ob- 

 viously rather indistinct pits; the form I am familiar with has pits al- 

 most, if not quite, as well-defined as those of the Ferax group of species 

 of Saprolegnia. The American plants, too, apparently differ from those 

 which I have examined in the greater number of antheridial branches 

 and antheridia supplied to each oogonium, the color of the wall of the 

 oogonium, the structure of the oospore wall, and the size of the oospores. 

 Other noteworthy points of difference have been indicated by italics in 

 the description of the variety." 



