THE TRANSLOCATION OF PROTOPLASM 



77 



along the other hypha. A large vacuole may also be disrupted by 

 protoplasm flowing into it from a side branch (Fig. 45, A). In a 

 hypha exhibiting streaming return currents are sometimes seen. 



Fig. 44. — Rhizopus nigricans. Drawing of part of a mycelium grown upon nutrient 

 gelatine, to show protoplasmic streaming. The protoplasm and vacuoles are 

 flowing along a main hypha and one of its stouter branches in the direction 

 shown by the arrows. The moving vacuoles are convex in front and plane or 

 concave behind. In the smaller hyphae, at the moment, no streaming is 

 perceptible. Copied by the author in black-and-white from Arthur's pencil 

 drawing in his The Movement of Protoplasm in Coenocytic Hyphae. 



These are situated at the periphery of the hyphal cavity and carry 

 no vacuoles (Fig. 46, B). Streaming is due to the change in water- 

 content at the extremities of the mycelium and the movement is 

 more frequently seen toward aerial parts, including growing branches 



