USTILAGINALES 609 



are sunken in a sclerotium, with their tops and spore masses projecting 

 slightly above the surface. Unfortunately the life cycle has not been 

 studied. 



In the Ustilaginales, three types of life cycles may be distinguished. 

 The first type includes Ustilago Zeae, Doassansia Sagittariae and Graphiola 

 Phoenics; it is related to the micro- forms of the Uredinales and to Schizo- 

 saccharomyces octosporus of the yeasts. The structure of the peridial 

 walls of the Graphiolaceae also suggests a further development of the 

 aecidium of a micro- form of the Uredinales. This type of life cycle is 

 shown in the following diagram: 



1 F C R^ I 



Uninud£at5.nrycelium-*Smut sppres-+Promycelium-»-Uninucleate sprout mycelium 



Diagram XXXIX. 



The second type includes Ustilago violacea and the majority of the 

 smuts. It possesses no analog in the Uredinales; among the yeasts it 

 corresponds to the Saccharomycodes Ludwigii type, mutatis mutandis: 



1 



:eliu 



Binacleate myce*ium-7»Smut spores — ►Promycelium^Uninucleate sprout mycelium->Binucleate sprout mycelium 



Diagram XL. 



The third type is only known in Tuburcinia primulicola. It also has 

 no analog among the Uredinales: 



p c R . 



Uninucleate mycelium— <Conidia-^*Binucleate mycelium-^Smut spores— ♦Promyeelium— »Sporidia 



Diagram XIL. 



Cytologically, the life cycle of the smuts is just as labile as that of the 

 yeasts and rusts. As in these, species of the same genus behave entirely 

 differently, e.g., as Ustilago Zeae and U. violacea or Doassansia Alismatis 

 and D. Sagittariae, Tuburcinia Trientalis and T. primulicola. Shiftings 

 appear especially in end forms. 



As in the above, the actual relationships of the Ustilaginales have been 

 presented as objectively as possible; it will be attempted to interpret 

 them briefly. The smut spores, which always caryologically function 

 as zeugites, are the stable points in a multitude of forms; in this respect, 

 and also biologically, they are homologous to the teliospores of the Ure- 



