STRUCTURE. 49 



Some remain narrow and cylindrical, are very numerous, and 

 produce fine hairs (paraph yses) ; others, also very numerous, take 

 the form of club-like ampulla cells, and each one forms in its 

 interior eight free swimming oval spores. Those ampulla cells 

 are sporidiiferous asci. After the spores have become ripe, the 

 free point of the utricle bursts, and the spores are scattered to a 

 great distance by a mechanism which we will not here further 

 describe. New ampullas push themselves between those which 

 are ripening and withering ; a disc can, under favourable circum- 

 stances, always form new asci for weeks at a time. The num- 

 ber of the already described utricle-bearers is different, accord- 

 ing to the size of the sclerotium ; smaller specimens usually 

 produce only one, larger two to four. The size is regulated 

 by that of the sclerotia, and ranges, in full-grown specimens, 

 between one and more millimetres for the length of the stalk, 

 and a half to three (seldom more) millimetres for the breadth of 

 the disc.* For some time the conidia form, belonging to the 

 Mucedines, has been known as Botrytis cinerea (or Polyactis 

 cinerea). The compact mycelium, or sclerotium, as an im- 

 perfect fungus, bore the name of Sclerotium echinatum, whilst to 

 the perfect and cup-like form has been given the name of Peziza 

 Fuckeliana. We have reproduced De Bary's life-history of this 

 mould here, as an illustration of structure in the JMucedines, but 

 hereafter we shall have to write of similar transformations when 

 treating of polymorphism. 



The form of the threads, and the form and disposition of the 

 spores, vary according to the genera of which this order is com- 

 posed. In Oidium the mostly simple threads break up into 

 joints. Many of the former species are now recognized as con- 

 ditions of JZrysiphe. In Aspergillus, the threads are simple and 

 erect, with a globose head, around which are clustered chains of 

 simple spores. In Penicillium, the lower portion of the threads is 

 pie, but they are shortly branched at the apex, the branches 

 ,,-Deing terminated by necklaces of minute spores. In Dactylium, 



* De Bary, "On Mildew and Fermentation," p. 25, reprinted from " German 

 Quarterly Magazine," 1872; De Bary, ' ' Morphologie und Physiologic der 

 Pilze," (1866), 201 



