THE TRANSLOCATION OF PROTOPLASM 



81 



protoplasm. If a spore with a germ -tube, grown in the dark, is 

 subjected not only to bright light but also to an increase of pressure 

 and loss of water, the protoplasm in its entirety may flow out of the 

 germ-tube into the spore, leaving the germ-tube completely empty 

 and contracted (Fig. 47, A, a). If the plant is again placed in the 

 dark, the protoplasm re-enters the germ-tube and normal growth is 

 resumed (A, 6). In general, if a mycelium is grown in the light and 



Fig. 47. — Rhizopus nigricans. Effect of light and darkness on 

 germinating spores. A : a, the spore was germinated in a 

 shallow hanging drop in a partially closed van-Tieghem cell in 

 the dark and was then suddenly brought into the light, its proto- 

 plasm then flowed into the spore and left the germ -tube empty 

 and plicate ; b, the same spore and germ-tube after having been 

 placed in the dark again, the protoplasm has re-entered the 

 germ-tube and this has begun to grow again, the old plications 

 in the wall can still be seen. B : the spores a, b, c, and d germin- 

 ated in the light and were then placed in the dark ; the ends of 

 the germ-tubes then became dilated ; in c and d the dilatations 

 have persisted after normal growth has been resumed. Magnifi- 

 cation, 345. The drawings copied by the author from Plate I of 

 Raybaud's Influence du milieu sur les Mucorine'es. 



is then placed in the dark, the current of protoplasm flows in the 

 direction the reverse of that taken when a mycelium is grown in 

 the dark and then placed in the light. Movements induced by 

 light take place not only during the application of the light but for 

 some time afterwards. When spores are germinated in the light 

 and are then placed in the dark, the ends of the germ-tubes become 

 dilated and afterwards normal growth is resumed (Fig. 47, B). 

 When hyphae which have been grown in the dark are placed in the 

 light, the vacuoles and oil-drops increase in number (Fig. 48). In 

 long hyphae, as Matruchot had pointed out earlier, intraproto- 



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