ENDOMYCETALES 



159 



no migTation of the protoplasm out of the old ascus wall. However, the asci 

 produced on the approach of cold weather have the thickened wall and germi- 

 nate the following spring- as in P. niacrosporus (Dangeard 1906, Biiren 1918). 



In the second genus, Taphridium (Volkartia), the asci are not scattered ir- 

 regularly throughout the host tissue but form a continuous layer just under the 

 epidermis, suggesting the beginning of ascocarp formation, protecting the 

 young asci by a layer of host tissue. Germination is immediate, the fungus 

 being carried over the winter by the mycelium in the roots. This line of 

 ascocarp formation finds fuller expression in the next family. 



Taphrinaceae. — (Exoascaceae of many earlier writers.) This family is 

 strictly parasitic on flowering plants, but a discussion is included here to show 

 the culmination of the line of development through the Coccidioideaceae and 



3 



Fig. 29. — Taphrina deformans. ], hynienium ; 2. intercellular mvcelium. 

 S, young" hymenium : .}, mature hvmenlum. (1 X670; 2 X600 ; 3, .} X330.) 

 1884 and Gwynne Vaughan 1922.) 



Taphrina OMvea. 

 (After Sadebeck 



Protomycetaceae and because several of the earlier writers incorrectly re- 

 ferred organisms to this group (e.g., the term exoascoses frequent in French 

 texts before the war). Also, this family is the only one of the group whose 

 cytology has been studied carefully. A knowledge of this cytology may prove 

 suggestive in Avhat to expect in the other families, although one should be ex- 

 tremely careful in assuming a similarity between different families of an order. 

 In Taphrina deformans, the peach leaf -curl (Dangeard 1894, 1896, Eftimiu 

 1927, Fitzpatriek 1934). The sprout mycelium winters over in the bark and 

 its cells are washed into the opening leaf buds in the spring. The germ tube 

 penetrates the young leaf and the resulting mycelium becomes binucleate in 

 some unknown manner. It stimulates the unfolding leaves to unequal growth 



