STUDIES IN SYMBIOSIS. 1.. 



beeoming more abundant as the process of disorganization of the hyphae con- 

 tinues. The final appearance of the fungTis is an irregular mass of no definite 

 structure, but staining deeply as if considerable proteid were present (Text-figs. 

 20, 25). At this stage of destruction of the mycelium I could not distingniish 

 any definite hyphae, but in some cases of final destruction, small droplets of a 

 yellowish highly-refractive substance were present in the host-cells. The whole 

 appearance of the -host-cell with its mycelium suggests the hypothesis that the 

 cytoplasm of the cell digests and causes the gradual destruction of the fungus. 

 This destruction of the mycelium is particularly apparent just prior to and dur- 



Text-fig. 24. — Hyphae penetrating from passage-cell into the cortex- 

 The appressorium-like swelling of the hyphae where it 

 abuts against the cell-wall is distinctly shown. The 

 hypha entering the inner cell shows a pronounced con- 

 striction at the point of perforation (x 450). 



Text-fig. 25. — A cortical cell containing the disintegrating fungus — a 

 few hyphae are growing towards adjacent cells. The ap- 

 pressorium-like structure is shown in one of them (x 450). 



Text-fig. 26. — A group of outer cortical cells containing very swollen 

 hyphae and spore-like bodies which form upon the ends 

 of these hyphae. The normal hyphae pass from the 

 inner cell (a) to the outer cells (b) and (c), hence cer- 

 tain hyphae pass outwards from the cortex for reproduc- 

 tion of the fungus (x 450). 



ing the development of the flowering shoot, as if an extra supply of proteid 

 were necessary during this active period. 



The digestion * and disintegration of the hyphae in the host-cell begins in 

 the centre of the mass and gradually extends outwards. 



*The term "digestion" is here used in the same sense as in the case of 

 Leguminous bacteroids. The organic structure of the mycelium is destroyed, and 

 this is probably the result of partial solution, or transformation by means of an 

 enzyme produced by the host-cell. 



