40 



THE SAPROLEGXIACEAE 



5. Saprolegnia ferax (Gruith.) Thuret. Ann. Sci. Nat. Bot., Series 3, 



14: 214, pi. 22. 1850. 

 Achlya prolifera Pringsh. Nova Acta Acad. C. L. C. N. C. 23: 395, 



pis. 46-50. 1 85 1. 

 Saprolegnia dioica Pringsh. Jahrb. f. wiss. Bot. 2: 206, pi. 22, figs. 



1-6. i860. 

 Saprolegnia dioica xslY. racemosa de la Rue. Bull. Soc. Imp. Nat. 



Moscow 42, 1: 469. 1869 (see Fischer, p. 336). 

 Saprolegnia Thiireti deBary. Abh. Senckenb. naturf. Ges. 12: 



326, pi. 5, figs. i-io. 1881. Also in Alorph. u. Phys. der Pilze, 



IV Riehe: 102. 1881. 

 Saprolegnia bodanica Maurizio. Jahrb. f. wiss. Bot. 29: 107, pi. 2, 



figs. 52-59a. 1896. 

 ? Saprolegnia esocina Maurizio. Jahrb. f. wiss. Bot. 29: 82, pi. i, 



figs. 4-17. 1896. 



Plates ii and 12 



Hyphae moderately stout and vigorous, irregular, sparingly branched 

 below. Sporangia plentiful, only slightly enlarged, typically wavy and 

 bent and of unequal diameter, often tapering upward, rarely almost 

 cylindrical, often proliferating laterally from below old ones; zoospores 

 about 91J. in diameter. Gemmae not very abundant, more or less elon- 

 gated usually, but varying to bulbous, or pyriform and sometimesjointed. 

 There is a strong tendency to the formation of long tapering tips on 

 the ends of stout threads, the ends of which are later cut ofT as rejected 

 tips of irregularly tapering gemmae below. In such cases the gemma 

 opens later by basal protuberance as is also usually the case even when 

 no tip is cut off. Oogonia numerous, varying in diameter from 37 to 

 97[x, the wall only about i.3-i.6[i. thick, but with numerous conspicuous 

 pits, which are about 4.5-5.5[j. in diameter; either lateral on stalks which 

 are usually short and frequently curved, or terminal on the main branches, 

 sometimes intercalary, but not in chains; spherical to slightly oval with a 

 basal neck, which is often curved ; not rarely formed inside of empty spor- 

 angia, and then cylindrical; thread-like extensions of the oogonia, con- 

 taining a single row of elliptic eggs, are not rare. Eggs centric, 1-20, 

 mostly 4-16, the diameter 24-30.5^, (rarely as small as 14.8^1 or as large 

 as 33.8;j.), the greater number about 261;., extremes sometimes occur- 

 ring in the same oogonium. Antheridial branches short, stout, mostly 

 androgynous, present in nearly all cultures in varying number, usually 

 on about 10-15% of the oogonia, but the number of oogonia furnished 

 with them varies from none to 98%, depending on the medium used. 

 The antheridia arise as a rule from the same main strands that bear 

 their oogonia, but often also from the oogonial stalks, and in the latter 

 case usually applying themselves not to their own but to nearby oogonia, 

 either from the same or another strand. Antheridia usually cut off, 

 short and tuberous, not more dense than the threads; fertilizing tubes 

 suppressed or very rare. 



