i 3 8 RESEARCHES ON FUNGI 



In a further set of experiments with mycelia growing in hanging 

 drops of dung-agar, the cover-glass was removed from a van- 

 Tieghem cell, inverted, and placed on a slide under the microscope. 

 Then, with a beading needle, one or more particular cells, without 

 their walls being broken, were pressed upon or bent until they were 

 dead. As a cell died, its vacuoles disappeared, its protoplasm 



kftWM^tt s 





1&3 



B 



a^SSsi 



SB^:;v,-iSS^^ 



A'-i/-" 



Fig. 71. — Pyronerna confluens. Diagram showing stages in the union 

 of two living parts of a mycelium brought about by the growth 

 of hyphae through a cell killed by a mechanical operation. 

 A : three cells in a mycelium, all containing granular protoplasm 

 and large clear vacuoles attached to the cell-walls. B : the 

 middle cell a has just been killed as a result of being touched and 

 moved by a needle ; its protoplasm has become disorganised ; 

 the two septa, b and c, which in A were plane and had open 

 pores, have now become convexly bulged into the dead cell and 

 their pores have become plugged. C : about 40 minutes after 

 B ; a hypha has grown from each of the remaining living cells 

 into the dead cell. D : about two hours after B ; the two new 

 hyphae have met and fused. Magnification, 446. 



became disorganised, its turgidity became reduced to zero, and its 

 bounding septa became concavo-convex and crowned with a plug 

 (Fig. 71, A and B). About half an hour after a cell with an intact 

 cell-wall had been killed, often an intrahyphal hypha began to 

 grow out from one of the septa, or from both, into the cavity of the 

 dead cell (Fig. 71, C). When two intrahyphal hyphae grew toward 

 one another simultaneously, as shown diagrammatically in Fig. 71, 

 D, and in an actual case in Fig. 72, A, they usually met near the 

 middle of the dead hypha and fused with one another. In this way 



