THE TRANSLOCATION OF PROTOPLASM 147 



lining the cell-wall and preserving the celFs turgidity. About two 

 and one-half hours after the cell first came under observation, it 

 suddenly died. As death took place, the septum had its pore 

 plugged up and was pressed forward convexly into the dead cell by 

 the adjacent living cell (Fig. 74, E). At the same time, the dead 

 cell lost its turgidity, for it suddenly shortened by about 9 per cent, 

 of its original length and also became narrower. 



The mycelium of Rhizoctonia solani grows rapidly in a radial 

 direction in a dung-agar plate (4-5 mm. per day) and, doubtless, 

 this rapidity of growth is a factor in permitting one to see streaming 

 through the hyphae. The observations of myself and of others 

 indicate that in the Phycomycetes, the Discomycetes, and the 

 Pyrenomycetes, the rate of growth in length of the mycelial hyphae 

 and the rate of flow of the protoplasm are correlated : the faster 

 the growth, the faster the flow, and the slower the growth, the 

 slower the flow. Doubtless this rule holds for the Hymenomycetes 

 also. 



When Rhizoctonia solani is growing under natural conditions in 

 the field, it may well be that the protoplasm of the ordinary long 

 hyphae which branch and grow over the surface of the Potato 

 tubers streams to the short irregularly anastomosing cells which 

 loosely or compactly make up the tissues of the sclerotia. 



The streaming of protoplasm along the cells of a hymenomycetous 

 fruit-body has not yet been observed, but there is every reason to 

 suppose that it takes place there just as in mycelia. The mechanism 

 by which the cytoplasm and the four nuclei of a basidium-body of 

 a Coprinus, a Collybia, or other agaric are transferred through the 

 narrow channels of the sterigmata into the four spores is essentially 

 the same as that by which protoplasm is transferred from some 

 hyphae of a mycelium of Rhizoctonia solani to others, for it depends 

 on the increase in size of a vacuole. Young basidia about to pro- 

 duce spores are full of protoplasm (Fig. 75, A). When the spores 

 are being formed, a number of small rounded peripheral vacuoles 

 come into existence in the stalk of the basidium-body (B) and fuse 

 together to form a single vacuole (C). This vacuole enlarges and, 

 pari passu, the cytoplasm and the four nuclei are pushed out of the 

 basidium-body into the four spores (C). Finally, the basidium-body 



