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Transactions. 



hvphae within the prothallus and those in the surrounding humus. A 

 great outward growth of hyphae was noticed from the surface of teased-up 

 portions of young rhizomes which had been kept for some days in water 

 in a watch-glass, and many of the threads showed what seemed to be single 

 round spores at regular distances along their length. At its uppermost 

 limit the hyphae of the mycorhiza in the interior cells of the prothallus 

 are scantily developed, but farther back the coils become more dense. 

 Throughout the greater part of the prothallus the fungal contents of each 

 cell show as a dense globular mass, in which the identity of the hyphal 



Fig. 9. — Old withered prothallus. carrot form, attached to plantlet which is broken 



above and below. X 3. 

 Fin. 10. — Old withered branched prothallus, attached to plantlet from which aerial 



stem is broken off. X 2. 

 FlG. 11. — Very young complete prothallus, showing original end intact and antheridia 



on its head. > 4~>. 



threads can no longer be traced. These globular contents of the cells 

 present a very characteristic feature both in the prothallus and young 

 rhizome. (See Plate II.) 



Not a few well-grown prothalli showed the original point of growth 

 almost intact, and the remains of the first-formed filament, which arises, 

 presumably, immediately from the spore, could be very clearly seen 

 (figs. 1a, 4a, 11, 12, and 13). In two instances — namely, the very young 

 prothallus shown in fig. 11 and the much older one in fig. 1a — there 

 was present at the extremity of the basal end a short filament of cells, two 

 or three in length, which in the former case was seen to be incomplete, 



