CLASSIFICATION 149 



to form hyphae, two nuclei arise bv mitosis and pass into the 

 germ tube, and that all subsequent divisions are conjugate. If 

 the spores bud to form secondary spores, however, the cells re- 

 main uninucleate whether the cultures originate from monosporic 

 or polysporic cultures. Wieben (1927) reported that buds con- 

 jugate in cultures of T. epiphylla and T. klebahni, thus resulting 

 in paired nuclei. 



Wieben (1927) showed that infection of the host is possible by 

 T. epiphylla and T. klebahni only if the penetration tube arises 

 from tw^o spores that have fused. Fitzpatrick (1934), however, 

 found that a single spore of T. deformans can cause infection. 

 These divergent results may be interpreted to indicate that some 

 species of Taphrina are homothallic, others heterothallic. 



Artificial cultivation. Among the older mycologists to re- 

 port growth by budding in liquid media are Brefeld and Sade- 

 beck (1893). Pierce (1900) grew T. dejormmis on malt extract, 

 beer, and various sugar solutions. Klebahn (1923) grew T. 

 tosqiimetii, T. epiphylla, T. sadebeckii, and T. aiirea on agar 

 fortified with salep. Mix (1924) grew T. defonnans on agar 

 media containing decoctions of potatoes, carrots, corn meal, rice, 

 or beets, and also on those containing the common carbohydrates. 

 Martin (1940) also grew this leaf -curl fungus on a variety of 

 media. On these artificial media the fungus growls in veast-like 

 fashion, and some of the cells in old cultures become thick-walled 

 (chlamydospores). Mix (1924) kept T. deforma?is in culture 

 for 22 months without loss of its virulence. 



Classification. There are no comprehensive recent treatises 

 on the taxonomy and classification of the Taphrinaceae. Sade- 

 beck (1893) placed in Exoascus those species with a subcuticular 

 ascogenous layer and perennial mycelium, and in Taphrina those 

 whose mycelium is annual but which are otherwise like Exoas- 

 cus. In Magnusiella he placed those whose asci arise from inter- 

 cellular mycelium without the formation of a subcuticular layer. 

 Giesenhagen (1895) distinguished four types on the basis of the 

 shape of the ascus: (a) filicina type, with slender cylindrical 

 asci; (b) betulae type, with plump cylindrical asci; (c) pruni 

 type, with long clavate asci; and (d) magnusiella t>^pe, with large 

 globular, oval, or saccate asci. Since asci in which the spores bud 

 profusely change shape, good morphologic features to distinguish 



