THE TRANSLOCATION OF PROTOPLASM 107 



to cell. The solution of this problem is not difficult. It is true 

 that, when one looks down on the septa of a hypha in a horizontally 

 disposed mycelium, such as that shown in Fig. 59, each septum 

 appears as a continuous plate seen edgewise. However, if streaming 

 is taking place and one studies the movement of the numerous 

 protoplasmic granules with a sufficiently high power of the micro- 

 scope, one observes that the protoplasm passes through the septa 

 in such a way as to leave no doubt that each septum is perforated 

 centrally and that the perforation or pore is circular in outline and 

 about 1 n in diameter. Often, when the vacuoles are not moving, 

 one can perceive a cone of moving protoplasm passing toward a 

 pore and a reverse cone passing away from the pore. Such cones 

 are similar to those of Pyronema co?tfluens, which will shortly be 

 illustrated and described in detail. Very convincing evidence that 

 each septum is normally perforated by a small open pore is afforded 

 by the mode in which the vacuoles, when carried along by the 

 protoplasm, pass from cell to cell. 



Passage of Vacuoles through the Pores in the Septa.— When 

 streaming in the mycelium of Fimetaria fimicola is relatively rapid, 

 the vacuoles are forced out of their usual fixed positions and may 

 be carried by the protoplasm for long distances. The way in which 

 the vacuoles pass through the septa was studied in larger hyphae 

 having a diameter of about 10 /x. and it is illustrated in Fig. 60. 

 At A in that Figure is shown diagrammatically in longitudinal 

 median section a hypha in which a dense stream of granular proto- 

 plasm is flowing from cell to cell and carrying vacuoles with it. 

 Each septum is perforated by a central open pore. A vacuole may 

 pass through the pore of a septum in pieces («-/) or as an unbroken 

 whole (g-l). In the first case a vacuole may be held before a pore 



Fig. 60— cont. 



rounded itself off and is stationary, while other vacuoles are approaching it ; 

 /, the vacuole in front of the septum is about to be increased in size by fusion 

 with another smaller vacuole which is now touching it ; g, a larger vacuole is 

 being carried by the protoplasm toward the septum ; /;, the vacuole has been 

 brought to the septum and has been flattened out against it ; i, part of the 

 vacuole has been forced through the pore of the septum ; j, one-half of the 

 vacuole has passed through the pore ; k, nearly the whole of the vacuole lias 

 passed through the pore ; I, the vacuole has passed through the pore in its 

 entirety and is being carried by the streaming protoplasm along the next cell. 

 Magnification, about 1000 ; the hypha is about 10 fi in diameter. 



