ERYSIPHE 01DIUM. 129 



more delicate thread, which then gave off a cell of one- 

 fourth of the diameter of the original one. 



Grawitz's experiments were performed at a time when 

 there were no trustworthy methods of isolating individual 

 fungi from a mixture of organisms, such as are usually pre- 

 sent 011 the affected skin, and hence they urgently require 

 repetition with better methods, and the asserted identity is 

 rendered very doubtful by the result of experiments made 

 with other mould fungi. Oidium lactis flourishes only com- 

 paratively imperfectly at the body temperature, and therefore 

 its parasitic existence on the surface of the body is improbable. 



In the lower animals affections occur very similar to Fungus of 

 favus in man, and in these the causal agent has of late 

 been cultivated pure. Such are the fungus of tinea galli 

 and that of the so-called favus of mice. The first has 

 been studied by Schiitz ; it leads to the formation of 

 whitish grey round patches on the comb and wattles of 

 fowls, which gradually merge together and spread on to 

 the neck, breast, and trunk. By continued cultivation 

 on nutrient jelly Schiitz succeeded in obtaining pure 

 from the scales on diseased combs a fungus which forms 

 a white mycelium, gradually liquefies the gelatine and 

 causes it to assume a reddish colour. It grows also 

 on potatoes, bread paste, &c., and best at a tempera- 

 ture of about 30 C. Microscopically the mycelium 

 consists of segmented and often branched threads of very 

 various dimensions ; not uncommonly these threads 

 show small warty or pedunculated projections ; some of 

 the segments are also globular, while others are lying free, 

 and occasionally provided with processes. Again, in some 

 cases fine shoots are seen on the sides of the rnycelial 

 threads, these shoots bearing one or two globular 

 greyish coloured bodies. Whether these or the spherical 

 bodies, or neither of them, are to be regarded as spores 

 is as yet uncertain ; the position of the fungus is there- 

 fore doubtful, and it is only the microscopical similarity 

 of the mycelium and the simple separation of the cells 

 supposed to be spores that has led to its provisional 

 inclusion among the forms of oi'dium. Inoculation of 

 pure cultivations of the fungus gave rise to the charac- 



9 



