i 34 RESEARCHES ON FUNGI 



but they are easily overlooked unless one is interested in them. 

 Ternetz, 1 if one may judge by her silence about plugs and by one 

 of her illustrations, probably saw plugs but confused them with 

 Woronin bodies. 



Plugs are formed in Fimetaria fimicola in just the same way as 

 they are in Pyronema confluens. This observation suggests that 

 the plugging of pores is a phenomenon of wide occurrence in the 

 Pyrenomycetes. 



Some cells of a mycelium of Coprinus sterquilinus growing in 

 a hanging drop of cleared dung-agar were killed with a needle. 

 Septal walls dividing a living cell from a dead cell were then examined 

 and, although the hyphae were much thinner than those of Pyronema 

 confluens and Fimetaria fimicola, in a number of cases a very tiny 

 plug was seen crowning the apex of the bulging wall. The inference 

 from these observations is that each septum of C. sterquilinus has 

 a central pore normally open but readily closed when one of the 

 two cells adjacent to it dies. In Rhizoctonia solani (= Corticium 

 solani), another Hymenomycete, the formation of a plug at the pore 

 of a septum at the moment when one of two adjacent living cells 

 died was actually observed (vide infra, Fig. 74, D and E, p. 145). 



The Origin of Intrahyphal Hyphae from Septal Walls and their 

 Growth through Older Dead Hyphae under Experimental Con- 

 ditions. — Intrahyphal hyphae, i.e. younger more slender hyphae 

 running through the cavities of older thicker dead parts of hyphae, 

 have been observed by many investigators. In 1881, Zopf 2 

 recorded them as occurring in Chaetomium Kunzeanum, one of 

 the Pyrenomycetes. In his description of the germination of the 

 gemmae, which are formed by the concentration of protoplasm in 

 certain cells in an old mycelium, he says : the germ-tubes originating 

 from the septa " take their way through the emptied neighbouring 

 cells of the mycelial hyphae, boring through the cross- walls where 

 they find them (Figs. 24, 25, A and B). Often empty hyphae for 

 wide stretches are quite filled with germ-tubes bent here and there. 

 Fig. 25, B, gives an idea of this. On seeing such illustrations one 



1 C. Ternetz, lor. cit., Taf. VII, Fig. 5. This should be compared with my Fig. 72. 



2 W. Zopf, " Zur Entwicklungsgeschichte der Ascomyceten : Chaetomium," 

 Nova Acta Acad, Cues. Leop.-Carol, Bd. XLII, 1881, p. 243, Taf. XVI, Figs. 23-25. 



