12 THE PHYCOMYCETES 



formed into resting sporangia. Tisdale (1919) noted that the 

 resting sporangia hibernate within leaves and stalks and that each 

 emits 20 to 30 swarm cells through a circumscissile pore. Ac- 

 cording to Sparrow (1934), these swarmers produce ecto- 

 sporangia (temporary sporangia), which are anchored to the 

 host; from them come what may be presumed to be true gametes. 

 These gametes fuse in pairs, the zygote infects the corn, and 

 resting sporangia eventually are again formed. 



Urophlyctis alfalfae induces the formation of galls near the 

 eround level on alfalfa and burr clover. The thallus consists of 

 a series of top-shaped, thick-walled cells, each provided with a 

 crown of haustoria. Each cell is a resting sporangiuni that germi- 

 nates when conditions are favorable. The zoospores escape 

 through a papilla; each is provided with two flagella, one about 

 5 i-i long and the other about 10 times as long. These zoospores 

 are presumed to conjugate before infections of suitable host tis- 

 sues. The morphology and pathogenicity of this organism were 

 carefully studied by" Wilson (1920) and Jones and Dreschler 

 (1920).' Since so few Cladochytriaceae have been studied in- 

 tensively, the development and sexuality of its members are not 

 well understood. 



Hyphochytriaceae. The Hyphochytriaceae include a few 

 species of doubtful relationships. The rhizomycelium is coarse, 

 and the apical portion becomes the zoosporangium. Macrochy- 

 trhim botrydioides, first found growing on decaying apple, typi- 

 fies the family. When its sporangia are mature, each opens with 

 a Hd, quite as in the resting sporangia of Physoderma and Cla- 

 dochytrium, and the contents escape in a vesicle or are freed 

 directly. Resting sporangia, however, are unknown in AL botry- 



dioides. 



Alacrochytrium has somewhat the appearance of the Rhizi- 

 diaceae and the Leptomitales and may well be a link between 

 the Chytridiales and Leptomitales. 



LITERATURE CITED 



Barrett, J. T., "Development and sexuality of some species of Olpidiopsis 

 (Cornu) Fischer," Ann. Botany, 26: 209-238, 1912. 



Butler, J. B., and A. Humphries, "On the cultivation in artificial media of 

 Catenaria angiiilhdae, a Chytridiacean parasite of the ova of the liver 

 fluke, Fasciola hepatica;' ScL Proc. Roy, Dublin Soc, 20: 301, 1932. 



