ACIIVI.A 



!07 



Not rare in cool or cold weather in springs, branches, and edges of 

 marshes, as in Arborctinn spring and branch, and in Glen Biirnie marsh. 

 Collected 24 times in Chapel Hill between February 15, 1912, and Deci'mher 

 15. 1913 (see table on p. 14), and many times since. Also found near Yadkin 

 College, N. C, by Totten, and reported from Amherst, Mass., by Hum- 

 phrey, and from Washington County, .Michigan, by Kauffman ('15, p. 

 195). For other illustrations see Cornu ('72), pi. i, figs. 2-8; Humphrey 

 ('92), pi. 19, figs. 92-95; Pringsheim ('73), pi. 19, figs. 1-15; pi. 21, figs. 

 I, 2, 13; pi. 22, figs. 1-3; also ('83a), pi. 7, figs. 10-20; Zopf ('84), pi. 20, 

 figs. 1-9 (oogonia parasitized by Rhizidiomyces); Petersen ('10), fig. 31 ; 

 Minden ('12), fig. 2a on p. 520. 



Easily distinguished from all other species, except A. colorata, A. 

 spiiiosa and A. radiosa, by the position and behavior of the antheridial 

 branches, and remarkable in being the only species except A . colorata in 

 which the antheridial branches may come from the oogonia themseh-es. 

 Easily distinguished from A. colorata by the always smooth oogonial 

 wall, and by the much smaller eggs which reach a higher number. For 

 experiments with this species in various media see Pieters ('15b, p. 529). 



Achlya lignicola is considered a synonym of A. raceniosa by Fischer, 

 Humphrey, Minden, and others, but Hildebrand's ('67)careful observations 

 on apparently abundant material indicate a variety that we will call var. 

 lignicola (Hildb.), which is distinguished by the more slender and less 

 branched mycelium (growing on wood) ; and by the smaller oogonia which 

 are borne ordinarily on the end of long slender hyphae, less often on short, 

 lateral branches, but e\-en then not racemosely arranged. 



Hine ('78) describes a variety (without name, p. 140, pi. 6, figs. 

 I-14) which seems to differ from others in the frequent appearance of 

 cylindrical intercalary oogonia with a single row of eggs. 



Minden treats Achlya colorata as a variety or form stelligera oi A. 

 racenwsa, and adds two other forms of his own (the second we take to be 

 a form oi A. colorata), as follows ('12, p. 548): 



(a) Forma niaxima. 



Oogonial wall smooth or very seldom with a single projection; up 

 to 8 antheridia and 12 eggs. This form, in its large number of antheridia, 

 resembles A. lignicola. 



(b) Forma Pringsheimii. 



Oogonial walls \-ery thick and yellow-brown, mostly with few pro- 

 jections which may gi\-e the oogonia an angular appearance; oogonial 

 stalk often very short; antheridial branches often springing from the 

 oogonia themselves, and at times from the main hyphae. With few, 

 often only 1-3 eggs. 



