in] 



PLECTASCALES 



73 



enclosed them between glass plates so as to reduce the entrance of air, and 

 the development of conidia. Similarly Zukal a few years later obtained 

 sclerotia by excluding air. The formation of the perithecia in Brefeld's 

 material was initiated by the appearance of pairs of simple, stout hyphae 

 which twisted round one another (fig. 32), and from one or both of which 

 branches later arose. Brefeld regarded them as possibly oogonial and 

 antheridial. 



A further study of these organs, the simple form of which suggests 

 a comparison with Gymnoascus, is much to be desired. Penicillium glaucum 

 includes several biological species or strains, and it is quite possible that 

 Brefeld's success depended not only on 

 the methods employed, but also on the 

 use of a fortunate variety. 



Klocker, in 1903, obtained asci in his 

 new species P. Wortmanni, and another 

 new and very curious ascigerous species, 

 Penicillium vermiculatum, was described 

 by Dangeard in 1907. The vegetative 

 cells, unlike those of related forms, are 

 uninucleate and bear a very scanty supply 

 of conidia. Perithecia are abundant; in 

 their initiation two branches take part. 

 The oogonium is at first uninucleate but 

 as it elongates the nucleus undergoes 

 several divisions. In the meantime a 

 second branch appears, usually borne on 

 a narrower filament ; it cuts off a uninu- 

 cleate or occasionally binucleate terminal 

 cell which applies itself to the middle of 

 the oogonium, and the intervening walls 

 disappear (fig. 33). Apparently, however, 

 fertilization does not take place ; the nu- 

 cleus of the terminal cell is described as 

 degenerating in situ while the oogonium 

 undergoes septation and is transformed 

 into a row of usually binucleate cells. 

 Narrow vegetative hyphae grow up around 

 this structure, and the perithecium is 

 formed in the usual way. 



The archicarp of this species shows 

 no importantpeculiarities but the terminal ^'S- 33- Penicillium vermiadatum 



, ^ It r ,1 .1 1 1 • Dang.; archicarp and antheridium; 



unmucleate cell of the other branch is after Dangeard. 



