ENDOMYCETALES 145 



Acid formed in raffinose, sorbite, and dextrin and a small amount of gas 

 in glucose and fructose. No action on any of the other common sugars and 

 glucosides. Malt gelatin liquefied slowly. On all liquid media, growth took 

 place at the bottom only, no pellicle formed, even after many months. 



Dipodascaceae.- — In Dipodascus, the mycelium is septate, but the cells are 

 coenocytic. The copulation of two hyphal cells produces gametangia (Fig. 

 22, 1-2). Fusion of the gametangial nuclei occurs without differentiation of 

 the gametes. The formation of diploid mycelium has disappeared and the 

 ascospores are formed in the gametangium without differentiation of an ascus 

 (Fig. 22, 3-7). From this stage we have two main lines of divergence, one 

 through Eremascus to the true yeasts, and one through Pericystis to the Coc- 

 cidioideaceae. A third possible line has ended blindly in Actonia, a genus 

 whose life cycle is not well known. 



In Actonia tropicalis, the mycelium is septate and may multiply by sprout- 

 ing. A round gametangium (sporangium) forms at the end of a filament and 

 develops small motile gametes (zoospores), which are apparently forced out 

 of the gametangium by the invagination of the basal wall. "Whether this 

 phenomenon is comparable to the proliferation of Ascoidea or is related to 

 columellar formation in the Mucorales is uncertain. The further fate of the 

 gametes ("zygospores") was not described. Whorls of sprout cells are some- 

 times produced on the hyphae. After some weeks on Kaulin's medium, asco- 

 spores (?) are formed. "At the end of a filament a round body appears with 

 a well-marked external capsule and a small green body in its center. This 

 body becomes flat and disklike, and from it four ascospores bud off. The four 

 ascospores are surrounded by a limiting membrane which is extremely diffi- 

 cult to see because of its transparency. The greatest care has to be taken 

 not to rupture the membrane. "When rupture does occur, the membrane is 

 coiled up under the parent cell and appears to be double" (Acton 1919). This, 

 if correctly reported by its author, is quite similar to the peculiar spore for- 

 mation we find in Paracoccidioides and reminiscent of partial sporangial forma- 

 tion in the higher Mucoraceae. "When the morphology and cytology of this 

 organism is better known, perhaps it will be found related to Paracoccidioides 

 and Histoplasma rather than to the Dipodascaceae. 



In Pericystis alvei (Betts 1912, Claussen 1921) the mycelium is differen- 

 tiated sexually, and copulation is heterogamous. Its cytology is unknown, 

 but the ascus is spherical and contains many spores, suggestive of conditions 

 found in the Coccidioideaceae-Taphrinaceae line. 



ACTONIA 



Actonia Dodge, n. gen. 



Mycelium cellulis curtis, crassis gemmiparis; zoosporangia terminalia, 

 zoosporis motilibus, sphericis, e zoosporangiis ab basis invaginatione ejectis;, 

 conidia verticillata, ovoidea gemmipara ; hypnosporae endogenae in hyphis 

 veteribus; asci terminales, spherici, tetraspori. 



