112 THE SAPROLEGNIACEAE 



foreign records of this species we have met with are by Petersen ('lo, p. 

 524), who reduces it to a form of A. polyandra de B. and calls it "forma 

 Americana," and by Minden ('12, p. 645) who reduces it to a variety of 

 A. deBaryana. The species differs easily from our interpretation of A. 

 deBaryana in the short androgynous antheridial branches, short-stalked 

 oogonia and smaller eggs. See under the genus and under A. imperfecta 

 for comparisons and discussions. 



This is the species that Humphrey studied with sections to deter- 

 mine the presence or absence of sexual fusion, and he came to the con- 

 clusion that no fertilization occurs ('92, p. 94). This conclusion is, 

 however, in all probability erroneous, as an examination of his own fig- 

 ures will show (see Trow '95, p. 638; and '99, p. 163). We have exam- 

 ined Humphrey's slides (not the cytological preparations) generously 

 lent by Dr. D. S. Johnson, and find his plant to be identical with ours 

 from Woods Hole. In two of Humphrey's figures (29a and 29b) ger- 

 minating eggs are shown. 



An Irish plant, considered a variety of this by Trow, has not been 

 found in America (see p. 139). It is probably of specific rank. 



7. Achlya Orion Coker and Couch. Journ. E. Mitchell Sci. Soc. 36: 100. 

 1920. 



Plates 34 and 35 



Hyphal threads long, reaching a length of 1.5 cm. on house-flies, 

 more slender than in most Achlyas, from io-40ij. thick close to base, 

 rarely up to 85[x thick, often wavy; usually little branched and pointed 

 at tips when young; becoming considerably branched with age. Spo- 

 rangia abundant, cylindrical, usually borne singly on the tips of the main 

 hyphae in young cultures, renewed by cymose branching, often forming 

 several clusters at regular intervals on the same hypha, irregular and 

 wavy in old cultures, 12-37 x 36-600;!, (rarely up to 900ii). Spores 

 9-iO[x thick, emerging as usual in Achlya, but often falling to the bottom 

 in an open group instead of forming a sphere at the sporangium mouth. 

 Oogonia abundant on flies, grubs, and vegetable media, spread over the 

 entire culture from the bases of hyphae to tips, giving the culture a lacy 

 interwoven or net- work appearance; the diameter 30-601A, commonly 

 32-48iA; usually borne singly on long, crooked, recurved stalks which 

 arise racemosely from main hyphae and which vary in length from 2-10 

 times the diameter of the oogonia; often oogonial stalks may branch 

 bearing two oogonia, and rarely oogonia may be borne on a stalk which 

 arises directly from another oogonial wall; very rarely intercalary; oogo- 

 nial wall usually without pits (except where the antheridial tubes enter) 

 when grown on flies or grubs, but as a rule with pits when grown on 

 boiled corn. Eggs 1-8, usually i or 2 in each oogonium; 25-45!!. in 

 diameter, most 33-3611, eccentric when ripe, with one large oil drop; 

 usually spherical, but often elliptical from pressure. Antheridial branches 



