BLASTOCLADIALES 613 



The elaboration of the life cycle in the Blastocladiales has been 

 thought by some investigators to indicate relationship with the algae. 

 The affinities of members of the order with the Chytridiales are so 

 much more pronounced, however, that one is forced to conclude, mere- 

 ly, that the Blastocladiales and the algae have, in the course of their 

 evolution, arrived at similar methods for insuring the beneficial effects 

 of cross fertilization. Although in all the Blastocladiales in which dis- 

 tinct sexual vegetative plants have been discovered similar sporophytes 

 and gametophytes are produced, species may yet come to light which, 

 like certain brown algae, develop dissimilar ones. 



Cytology and Physiology 



Little is known of the cytology of any of the Blastocladiales with the 

 exception of Allomyces (Barrett, 1912a; Lugg, 1929; Hatch, 1935, 1938; 

 Ritchie, 1947; Emerson and Wilson, 1949: Wilson, 1952). 



Cytological preparations of the zoospores of Blastocladiella simplex 

 are figured by Matthews (1937) and of Blastocladia pringsheimii and 

 Blastoeladia globosa by Cotner (1930a, b). Since Allomyces differs mark- 

 edly in several respects from other members of the order, its cytology 

 (Fig. 41, p. 622) is not representative of the group as a whole and is 

 discussed separately. 



Information is being rapidly accumulated concerning the physiology 

 of members of the order. Species of Allomyces and Blastocladiella have 

 been cultivated on a variety of solid and liquid media. A series of papers 

 has been published on their physiology: see Stiiben, 1939; Emerson 

 and Cantino, 1948; Cantino, 1948, 1949a, 1950, 1951a, 1952; Barner 

 and Cantino, 1952; Cantino and Hyatt, 1953a, 1953b, 1953c; Cantino 

 and Horenstein, 1955, 1956a, b; Brown and Cantino, 1955; Machlis and 

 Ossia, 1953a, 1953b; Machlis, 1953 a, b, c, 1957; Machlis and Crase- 

 mann, 1956; Cantino, Lovett and Horenstein, 1957: Turian, 1952. 



Investigations on Allomyces 



Results of several extensive investigations of the morphology, devel- 

 opment, cytology, life cycle, and distribution of Allomyces have not 

 only revealed facts of great general biological interest but have also 



