7 8 



RESEARCHES ON FUNGI 



and developing sporangia, than in the opposite direction. The 

 application to the mycelium of a drop of 20 per cent, solution of 



potassium nitrate causes vigorous 

 movement for a time toward the 

 place of application. The stream- 

 ing movement aids in the transfer 

 of nutrient materials to points 

 where growth is taking place, but 

 growth is not dependent on it, and 

 full and normal development may 

 take place without the movement 

 coming into action. 



In 1905, Schroter, 1 in a detailed 

 study of protoplasmic streaming 

 in Phycomycetes, added but little 

 to the description of the move- 

 ment as given by Arthur, but 

 determined with some precision the 

 role of the different factors which 

 cause the stream to flow. The 

 following is a summary of the 

 results of his investigations. The 

 streaming of protoplasm in Mucor 

 stolonifer ( = Rhizopus nigricans) 

 and Phycomyces nitens is dependent 

 upon osmosis and transpiration. 

 When a mycelium grows submerged 

 in a homogeneous substratum or 

 in air saturated with water vapour, 

 its protoplasm does not exhibit 

 streaming. Streaming begins only 

 when the medium has local differ- 



Fig. 45. — Rhizopus nigricans. Pro- 

 toplasmic streaming in mycelial 

 hyphae. A, the current from a 

 branch is rushing into a long 

 vacuole in the main hypha. 

 Further along the main hypha, 

 the protoplasm is pushing into 

 a large vacuole (only partially 

 shown). B, part of a highly vac- 

 uolated hypha with the proto- 

 plasm in motion : a just before, 

 and b just after, a change in the 

 direction of the current. Copied 

 by the author in black-and- 

 white from Arthur's pencil 

 drawing in his The Movement 

 of Protoplasm in Coenocytic 

 Hyphae. 



ences of concentration or when 

 transpiration becomes active. Subjection to dry air causes lively 

 streaming and hastens that already present owing to the increase 



1 A. Schroter, " Uber Protoplasmastromung bei Mucorineen," Flora, Bd. XCV, 

 1905, pp. 1-30. 



