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RESEARCHES ON FUNGI 



The bulging forward of a septal wall and the formation of a pore 

 plug are illustrated semi-diagrammatically in Figs. 67 and 68. In 

 Fig. 67 are shown : to the left, a septum with an open pore, seen 

 in face view ; and, to the right, parts of two adjacent cells of 



a hypha, seen in 

 median longitudinal 

 section. In these 

 cells, as indicated 

 by the arrows, the 

 main mass of the 

 protoplasm, which 

 is finely granular, is 

 streaming from one 

 cell to the next 

 through the pore of 

 the septum. Let 

 us now suppose that 

 by means of a 

 mechanical opera- 

 tion with a needle 

 the lower cell is 

 broken open and 

 killed. Then, as 

 shown in Fig. 68, 

 the septum is 

 pressed forward by 

 the living cell into 

 the dead cell, the 

 pore becomes 

 blocked by a plug, 

 and the protoplasm of the living cell ceases to flow through the 

 pore because the passage-way is no longer open. 



Other drawings showing convexo-concave septa provided with 

 plugs, facing cells which have been killed by mechanical operations, 

 are reproduced in Figs. 69, 70, 71, and 72. 



A septal plug closing a pore in a septum separating a living and 

 a dead cell of Pyronema confiuens is a discoid, somewhat plano- 



FlG 



68. — Pyronema confiuens. Diagrams illustrating 

 the plugging of a pore of a septum immediately 

 after a cell on one side of the septum has been 

 killed. To the right, parts of two adjacent cells of 

 a hypha in median longitudinal section. The two 

 cells were both living and the septum was straight 

 and provided with an open pore, as shown in 

 Fig. 67. The lower cell was then broken open and 

 killed by a mechanical operation with a needle. 

 As an immediate result, as here shown, the turgid 

 living cell pressed its cell-wall convexly forward 

 toward the dead cell, and the pore of the septum 

 became plugged, so that the escape of protoplasm 

 from the living cell into the dead cell was pre- 

 vented. To the left, in face view, a septum with 

 a plugged pore. Magnification, 3240. 



