EEYSIPHE 01DIUM. 



127 



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Oidium Tuckeri, the fungus of vine disease. A whitish 

 mildewy layer appears on brownish patches of the leaves and 

 twigs of the vine, and also attacks the young berries, whose 

 epidermis dies and bursts. The ^ 



longish round conidia are placed 

 singly on the fruit hyphae. 



Oidium lactis. Fruit hypha3, 

 single, upright, colourless ; form a 

 terminal chain of spores; at times 

 apparent formation of branches, the 

 fruit hyphae growing upwards along- 

 side the terminal chain of spores 

 already formed. Spores short, cy- 

 lindriform, 0'0077 O'OIOS mm. long 

 (fig. 16). Very widely distributed, 

 forming a whitish mouldy coating 

 on milk, bread, dung, &c. Flourishes 

 best between 19 and 33 C. (Hausen). 



In some parasitic skin affections 

 of man development of fungi lias 

 been for a long time observed, 

 and these fungi appear to have a 

 certain resemblance to the my- 

 celium and fructification of oidium. 

 Grawitz has in fact attempted to 

 prove by cultivations that the favus 

 fungus (Acliorion Schonleinii), the 

 fungus of Tinea tonsurans (Trico- 

 pbyton tonsurans), and the fungus 

 cf Pityriasis versicolor (Micros- 

 poron furfur) are identical with Oi- 

 dium lactis. According to Grawitz 

 the conidia of this fungus, when cul- 

 tivated artificially, form one or 

 several germinating tubes ; these 

 soon become segmented and send 

 out lateral branches which elong- Fig. l6.-0idium lactis. 

 ate by apical growth. The growth ^, older, B younger, fruit 

 ceases often after a very short, 

 often again after a longer time, and 

 segmentation of the threads into 

 conidia begins ; these conidia are 

 at first almost cubical cells, but later assume a lonoish ovi 



Oidium as tho 

 cause of Favus 

 and Tinea 

 tonsurans. 



hyphas. 

 s, chains of spores in the 

 neighbourhood of which 

 the fruit hyphas (h) con- 

 tinue to grow like a la- 

 teral branch. X 200. 



