SOJ, STUDIES IN SYMBIOSIS. 1., 



the hypha abuts against a wall. From this swollen end, one or more thin 

 hyphae penetrate an adjoining cell (Text-figs. 23, 24, 25). 



The Mycelium in the Cortex. — The infecting hypha enters a cortical cell and 

 passes towards the nucleus which is surrounded by a thick zone of the cell's 

 cytoplasm. It then branches and coils round the nucleus or close to it. At first 

 the cytoplasm of the hypha is sparse and stains very lightly with methyl violet; 

 it is vacuolated to a large extent. The hypha is very thin (Text-figs. 13, 14, 23). 

 As the nucleus moves in the cell, the hyphae grow with it and branch so that, 



Text-fig. 13. — Two cells of cortex with an early stage of infection. The 



hyphae aj^e clearly associated with the cell nucleus 



(x 167). 

 Text-fig. 14. — Aggregation of the hyphae around the nucleus (x 500). 

 Text-fig. 15. — A normal cortical cell showing the nucleus, cytoplasm 



and spherical starch-grains (x 40O) . 

 Text-fig. 16. — Partial digestion of the central hyphae, and the slight 



enlargement of others around. The nucleus enlarges and 



stains deeply (x 500). 

 Text-fig. 17. — Further stage in disorganization of the fungus, — nucleus 



enlarged (x 500). 



while the hyphae of the fungus seldom completely surround the nucleus, they 

 are invariably closely associated with it. The starch grains gradually disappear- 

 from the cell soon after infection by the fungus. No hypertrophy of the hyphae 

 takes place. They do not form vesicles or bladders in association with the 

 nucleus, but their contents become more abundant, and stain more deeply with 



