370 AQUATIC PHYCOMYCETES 



enlargement of the more proximal part of the germ tube, the incipient 

 sporangium arises behind the point of origin of the primary branches 

 of the rhizoids. Such a sequence needs further confirmation in other 

 species of Entophlyctis. 



Germination of the resting spores has been observed by Fisch 

 (1884a), Karling (1941b), and Haskins (1946). In all instances the 

 resting spore functioned as a prosporangium and an external, thin- 

 walled zoosporangium was produced. 



Specific concepts in Entophlyctis are by no means clear, and consid- 

 erable work must be done before they can be adequately defined. The 

 characters most used at present to distinguish species are the shape and 

 size of the sporangium, the number and, particularly, the place of origin 

 of the rhizoids on the sporangium, and the host. As Karling (1931a) 

 aptly points out, since very little is known concerning the range of var- 

 iation of a single species under different conditions in diverse substrata 

 (and, one may add, since little is known of the resting stage), no crit- 

 ical analysis can yet be attempted. 



KEY TO THE SPECIES OF ENTOPHLYCTIS 



Protoplasm colorless at maturity; coloration, if present, only in the 

 oil globule of the zoospore 

 Epibiotic cyst persistent, functioning in the discharge of zoospores 

 Rhizoidal system limited, delicate; on Chlamydomonas and Gloeo- 



cystis E. apiculata, p. 372 



Rhizoidal system extensive, coarse; on Spirogyra . E. bulligera, p. 373 

 Epibiotic cyst not functional, evanescent 

 Zoospores with an orange-colored globule 



Sporangium spherical or ovoid; rhizoids arising from one or 



more places on the sporangium E. rhizina, p. 374 



Sporangium variable in shape; rhizoids arising for most part 



from one basal axis E. texana, p. 375 



Zoospores with a colorless globule 



Rhizoids coarse, strongly dichotomously branched, main axes 



lateral; sporangium subspherical or oblong . E. pygmaea, p. 376 

 Rhizoids delicate, regularly or irregularly branched 



Rhizoids arising in most cases from a single basal axis; spo- 

 rangium spherical, broadly ellipsoidal, or pyriform; in 

 green algae 



1 See also the recently described taxon on p. 381. 



