THE TRANSLOCATION OF PROTOPLASM 165 



(1) the apical cell of the hypha is growing steadily and evenly in 

 length ; and (2) the protoplasm in the hypha is flowing continuously 

 through the pore of the septum into the apical cell and onwards 

 toward the growing point. 



In view of the observations just recorded we may conclude that 

 the cause of the temporary bulging forward of a newly formed 

 septum of Rhizoctonia solani is not the blocking of the septal pore, 

 but rather the pressure of the viscous protoplasm on the septum 

 becoming temporarily and considerably greater in the penultimate 

 cell than in the terminal cell. There can be no question but that 

 a septum with a tiny central pore must offer some resistance to the 

 flow of protoplasm from one cell to another, and in the bulging of 

 a new r ly formed septum we seem to be afforded evidence of this 

 fact. In an older part of the mycelium where the septa are straight, 

 it is possible that the septa are slightly thicker and stiffer than the 

 septa near a growing point and it may be that, in such a region of 

 the mycelium, the massive protoplasm is more labile than near the 

 growing points ; but all this remains to be decided by exact 

 investigation. 



An actively growing hypha of Rhizoctonia solani in which the 

 protoplasm is slowly streaming en masse toward the growing point 

 and in which two to five of the terminal septa are simultaneously 

 bulged forward toward the growing point presents us with evidence 

 which shows that protoplasm is being pressed by a series of cells with 

 considerable force toward the growing point and that there is a 

 decreasing pressure gradient for the protoplasm from the oldest cell 

 to the one last formed. 



After the temporary bulging-forward of newly formed septa had 

 been discovered in Rhizoctonia solani, the phenomenon was looked 

 for in the mycelia of other Higher Fungi. It could not be observed in 

 Fimetaria jimicola, Gelasinospora tetrasperma, or Pyronema con fluens, 

 but it was distinctly seen in the species of Ciboria that grows on 

 male Birch catkins. In this Ciboria a new septum was seen to bulge 

 forward slightly about six minutes after it had begun to form and 

 immediately after it had completed its development. The bulging 

 forward of newly formed septa is not so marked in the Ciboria as 

 it is in Rhizoctonia solani ; but, once again, in the Ciboria, just as 



