THE TRANSLOCATION OF PROTOPLASM 125 



plasm. However, in an older mycelium which has exhausted some 

 parts of its substratum but not others, it is easily conceivable that 

 the flow of protoplasm toward the apical growing points of the 

 elongating hyphae may be due : in part to vacuolar pressure arising 

 in older non-growing hyphae which are evacuating their labile pro- 

 toplasm, and in part to the formation of new protoplasm in those 

 cells which lie behind the growing points of the elongating cells and 

 are surrounded by a nutrient medium that is still unexhausted. 



The monoporous septum in the mycelium of a Higher Fungus 

 is comparable with the polyporous septum or sieve-plate in a sieve- 

 tube system of a Higher Plant ; and it may well be that the discovery 

 of the means by which colloidal matter is rapidly transported from 

 one part of a mycelium to another may help us to elucidate the 

 means whereby colloidal matter is rapidly transported from one part 

 of a sieve-tube system to another. 



Biological Significance of Streaming. — As we have seen, de 

 Vries, Arthur, and Schroter regarded streaming in the Phycomycetes 

 as an important means of transferring food material to points of 

 growth. Ternetz, in discussing the cause of the formation of 

 apothecia in Ascophanus carneus, after insisting on the importance 

 of a stimulus provided by a check in the supply of nutriment to the 

 mycelium, says that the hyphae which form the apothecia receive 

 nutriment from the mycelium in the substratum and that in this 

 process " the copious streaming of the protoplasm plays no small role. " 



With the views expressed by my predecessors as to the biological 

 significance of the streaming I am in entire agreement. My own 

 observations have taught me that, in Pyronema confluens and 

 Fimetaria fimicola, protoplasm is transported as such from hyphae 

 which have ceased to grow into hyphae which are growing vigorously. 

 I have not studied the development of the fruit-bodies of either of 

 these species but, with Ternetz, I am strongly of the opinion that, 

 during the growth of the fruit-bodies, the transference of the food- 

 materials from the vegetative mycelium into the fruit-bodies is largely 

 carried out by protoplasmic streaming. If this view is correct, the 

 translocation of protoplasm from cell to cell in the mycelium by 

 the process of streaming results in great advantage to the species in 

 which it occurs. 



