376 RESEARCHES ON FUNGI 



irregularly upon, the walls of the vacuoles, but do not enter the stream 

 of labile protoplasm when this is flowing from cell to cell. 



In Pyronema confluens, Fimetaria fimicola, etc., when a cell on one 

 side of a septum is killed with a needle or when it dies, the pore in the 

 centre of the septum is immediately closed by means of a plug of coagulated 

 protoplasm, so that the escape of protoplasm from the living cell through 

 the pore into the dead cell is prevented. At the same time, the septum 

 is bulged outwards from the living cell into the dead cell by osmotic 

 pressure. 



In Pyronema confluens, one or more cells in a hypha were killed with 

 a needle, with the result that intrahyphal hyphae grew out into them 

 from the septa of the adjacent living cells. Thus intrahyphal hyphae 

 have been obtained under experimental conditions. 



Intrahyphal hyphae originating at septa often fuse together in such 

 a way as to repair wounds made in a mycelium. 



Protoplasmic streaming in the Hymenomycetes has been observed for 

 the first time in the mycelium of Rhizoctonia solani (= Corticium solani). 

 Here the labile protoplasm is finely clouded with particles which the eye 

 can detect. Possibly in some Hymenomycetes, e.g. Coprinus sterquilinus 

 and C. lagopus, in which the protoplasm is very homogeneous, streaming 

 may never be detected. 



The biological significance of protoplasmic streaming in the 

 Hymenomycetes is the same as in the Pyrenomycetes and Discomycetes, 

 i.e. it serves to supply protoplasm to rapidly growing hyphae wherever 

 these may be situated. 



With the discovery that, in the Hymenomycetes, protoplasm can 

 flow rapidly from cell to cell through the pores of the septa, light is thrown 

 on the means whereby hymenomycetous fruit- bodies in general obtain 

 from the mycelium the nutriment required for their upbuilding and 

 obtain it so rapidly. 



Protoplasmic streaming in the Phycomycetes has been compared 

 with that in the Ascomycetes and Basidiomycetes. 



The septa formed in the mycelium of Rhizopus nigricans are, when 

 fully developed, imperforate. They are never formed across a hypha 

 which is full of protoplasm or in any position where they might be 

 a hindrance to protoplasmic streaming. A septum is formed at the base 

 of a terminal hypha or a system of terminal hyphae only after these have 

 evacuated their massive protoplasm ; and the columella- septum is 

 formed only after the sporangium has attained full size and has received 

 all the protoplasm required for the formation of the spores. 



Septa in the mycelia of the Higher Fungi and Fungi Imperfecti serve 

 as limits to the adverse influence of injuries to a mycelium. When a cell 

 is killed or dies, the septa protect the adjacent living cells from the effects 

 of the disturbance. 



The advantage in each septum of a Higher Fungus or Fungus 



