140 Scientific Proceedings, Roi/al Dublin Society. 



form numerous other spore-containing cavities by enlargements of the 

 processes. One must imagine a beet-cell when attacked sends out living 

 diverticula, which make a passage for themselves between the other 

 surrounding host-cells (stimulated thereby to division), and sooner or later 

 dilate to form the cavities or cysts, the whole being thus one malformed 

 host-cell. Througli tlie kindness of M. Trabut, I have been able to examine 

 some of the original material, and find myself unwillingly compelled to 

 differ from Magnus. Serial sections show the layer or layers of cells 

 between adjoining cavities broken or in the act of breaking down. Thus 

 the cavities containing the spores are due, I take it, at any rate in 

 part, to the disappearance by absorption of the surrounding host-cells. 

 They are therefore lysigenetic in origin, as is the case, to a certain extent, 

 in Urophhjcth pulposa (Wallr.) Schroet., and U. major Schroet., and still 

 more so in JJrophlyctis Ruhmameni Magn. (13). This is a point of con- 

 siderable interest. In 1895 von Lagerheim reported the occurrence of galls 

 on the roots of Lucerne {MecUcago satiim) in Ecuador. These galls were 

 caused, he stated, by the same fungus as that responsible for the beet 

 tumour. In the "Beriehte der deutsclien botanischen Gesellschaft" (14) for 

 1902, Magnus describes the same root-galls on lucerne material received 

 from Behrens from Colmar in Alsace, and finds certain points in which 

 the lucerne gall differs from the beet one, sufficiently important to justify 

 him in describing the lucerne fungus as a distinct species under the name 

 of UroiMyctis alfalfm (von Lagerheim olim) Magnus. The chief distinction 

 is that in TJ. alfalfm the walls between the cavities in the gall are broken 

 down, thus putting adjoining originally independent cavities into connexion ; 

 while in U. leproides, as already stated, no such dissolution of septa, 

 according to Magnus, occurs. My material, however, shows such collapse 

 of tlie separating partitions, and tlius U. alfal/ce as a distinct species must 

 rest, if I am right, on other grounds. Interesting in this connexion is 

 the illustrated account by S. Kusano (15) of a cyto-pathological study of 

 Synchytrlum puerarice. The parasite is chemotactically attracted to the 

 deeper tissues of the host, avoiding, though a Synchytrium, the epidermis 

 and the green cortical cells. Its plasmodium develops in the host'Cell. 

 Both increase much in size. The surrounding host-cells lose their walls 

 and form a symplast, enveloping the developing Synchytrium sorus, which, 

 at first intracellular, in the end lies in a lysigenetic intercellular space. 



Okigin of Besting Spores tn Ujiophlyctis. 

 The resting spore of Urophlyctis is a smooth, thick-walled body, com- 

 parable to a plano-convex lens in section. From the centre of the flattened 

 side a small papilla may project. There are two distinct views as to the 

 origin of these spores. Magnus has described in U. /eproides and other 



