86 Transactions British Mycological Society. 



From the main hyphae arise fine, profusely branched hyphal 

 threads, or "arbuscules" (Bernard, 1911; Magrou, 1921) which 

 degenerate into irregular granular masses or " sporangioles " 

 surrounding the main hyphae (Figs. 4 and 5). This granular 

 substance is insoluble in all the ordinary solvents, with chlor- 

 zinc-iodine it turns a reddish-brown colour, and with iodine a 

 yellowish-brown. The Mycosin test for chitin (Wisselingh, 1898) 

 was tried, and after this treatment the "arbuscules," "sporan- 



Fig. 3. Hyphae in the cells of the thallus showing method 

 of penetration of the cell-walls, x 770. 



gioles" as well as the walls of the main hyphae turned reddish- 

 violet with chlor-zinc-iodine, while the walls of the liverwort 

 turned blue, a similar result being obtained with iodine and a 

 trace of sulphuric acid. 



The growth of the fungus is restricted by the formation of 

 the "arbuscules" and their subsequent conversion into "spo- 

 rangioles." The infected zone is thus strictly localised, and the 

 fungus is prevented from becoming harmfully parasitic. No 

 marked activity of the nuclei in infected cells has been observed 

 as has been described by Burgeff (1909), Magnus (1900) and 



