7 6 RESEARCHES ON FUNGI 



had established the fact that the protoplasm is the essential living 

 substance of all animal and vegetable cells, that Schacht * showed 

 that it is the protoplasm which moves and not the sap and concluded 

 that streaming is but an outward and visible sign of protoplasmic 

 activity. 



The streaming of protoplasm in the mycelium of Phycomycetes 

 was first observed by Hugode Vries 2 in 1885 in the sporangiophores 

 of Phycomyces nitens, and he regarded it as an aid in the transfer of 

 nutrient materials to points where growth is taking place. 



In 1897, Arthur 3 published the results of his investigations on 

 streaming in Phycomycetes. His observations and conclusions may 

 be thus summarised. Streaming occurs in Mucor Mucedo, M. race- 

 mosus, Rhizopus nigricans, R. elegans, Phycomyces nitens, Sporodinia 

 Aspergillus, Thamnidium elegans, and Pilobolus crystallinus. The 

 movement (specially investigated in Rhizopus nigricans) is most 

 evident under moist conditions, takes place in hyphae which have 

 attained a certain maturity, at one and the same time is restricted 

 to some of the main hyphae and a few of their branches, and in- 

 volves the cytoplasm, microsomes, food-bodies, nuclei, and vacuoles 

 (Fig. 44). The current may be compared with that of a somewhat 

 viscous colourless fluid flowing through a pipe, but there is an 

 ectoplasmic layer of protoplasm lining the cell- wall, sometimes 

 visible but often not, which takes no part in the movement. The 

 streaming of the protoplasm is somewhat fitful. It starts, stops 

 without apparent cause, and then begins again either in the same 

 direction or, more often, in the opposite direction. The rate of 

 movement varies greatly, but at 28° C. it was found to average 

 3*3 mm. per minute, which is about twice as fast as the rotation in 

 Nitella and four times as fast as the circulation in Tradescantia. 

 In a rapidly moving current the vacuoles become more convex at 

 the anterior end and less convex, flat, or even concave at the posterior 

 end (Fig. 45, B). A large vacuole, on coming to a fork, is often 

 bisected so that one part goes along one hypha and the other part 



1 H. Schacht, Die Pfianzenzelle, 1852, p. 340.. Cited from Pfeffer. 



2 H. de Vries, " Uber die Bedeutung der Circulation und der Rotation des 

 Protoplasma fur Stofftransport in der Pflanze," Bot. Zeit., Bd. XLIII, pp. 1-6, 16-26. 



3 J. C. Arthur, " The Movement of Protoplasm in Coenocytic Hyphae," Annals 

 of Botany, Vol. XI, 1897, pp. 491-507. 



