EXOASCI. 



117 



Endomyces decipiens is a parasite in the fruit-body of Armillaria mellea ; 

 E. magmisii lives in the gelatinous, fermenting exudations of Oak-trees ; Asco- 

 corticium albidum, is found under the bark of the Fir-tree. Endomyces has 

 chlamydospores and oidia. 



The species of Taphrina are parasites, whose free asci may be 

 found in great numbers, generally closely pressed together, on 

 the parts of plants which they have att icked. The asci are de- 

 veloped directly from the ascogenous cells of a fertile, generally 

 sub-cuticular, hypha, which arises from the sterile mycelium. The 

 latter arises from the germinating ascospore, and may hibernate 

 in the tissues of its host, particularly in the winter buds, and then 

 with the commencement of the next period of vegetation it con- 



FIG. 104. Taphrina (Exoascus) 

 pruni. Yeast-like budding of a 

 germinating spore ( x 600). 



FIG. 105. Taphrina betulina: a ascus filled 

 with conidia; b germinating spores (x600). 



tinues its growth side by side with that of its host. The hyphge 

 ramify in the intercellular spaces or beneath the cuticle, but have 

 no haustoria. The ascospores (Fig. 105 A) and unripe asci may 

 produce conidia. 



Very remarkable appearances, and swellings of the attacked tissues, are pro- 

 duced when the mycelium is perennial; for example, the " Witches' -brooms " 

 and " Pockets." The hard, hollow, stoneless plums, known as " Pocket " or 

 " Bladder " Plums, are produced by considerable changes in the tissues of the 

 fruit ; these are caused particularly by T. pruni on several species of Prunus. 

 The " Witches'-brooms," on the contrary, are deformations of entire twigs or 

 branches, and often attain a very large size. They occur on Alnus incana, 

 caused by T. epiphylla ; on Carpinu* betulus, by T. carpini ; on Cherjy-trees, 

 by T. cerasi ; on Plum-trees, by T. insitities ; on Birches, by T. tuvyida and 

 T. betulina. T. deformam attacks the leaves of the Peach, and causes them 

 to curl. 



