1 6 Robinson, Puccinia inalvaceamm and its host plant. 



lucida, and the sections were then treated with sokitions 

 of common salt. A io% solution brought about plasmo- 

 lysis of both the invaded and uninvadcd cells, but on 

 replacing the sections in water no recovery took place. 

 When a 4% solution was used plasmolysis occurred as 

 before, in both the invaded and uninvaded cells, but later 

 treatment with water brought about complete recover)' 

 in both cases {PL II., Figs. 17, 18 and 19). This power 

 of the protoplasm of the cells invaded by the fungus to 

 contract under plasmolysis and recover again affords a 

 definite indication that the haustoria are lying in living 

 cells. In some cases of plasmolysis of cells invaded by 

 haustoria, the protoplasm of the cell was observed to 

 stream towards the nucleus along the line of the proto- 

 plasmic strandj which for a {q.\\ seconds became much 

 wider. Ultimately the cytoplasm aggregated near the 

 nucleus in the centre of the cell, though a fine pro- 

 toplasmic strand still remained connected with each 

 haustorium that had not reached the nucleus. It is 

 difficult to see how the entering haustoria could invariably 

 appear to be connected by protoplasmic strands with the 

 nucleus, unless they were actuall}' lying in the proto- 

 plasmic strand and growing along it {PL II., Figs. 22, 23). 

 Plasmolysis experiments were also tried with salt solu- 

 tions varying from i to 4%, in order to determine, if 

 possible, whether there was any appreciable difference in 

 the turgidity of invaded and uninvaded cells, but the 

 results were inconclusive. 



In the cells of all the tissues entered the haustoria 

 appear to grow towards the nucleus. This phenomenon 

 was first described b)' Rosen^' for Pnccinia asarina, and 

 Magnus,^- Guttenberg,'^ and other observers have confirmed 



i> Cohn's "Beitrage z. Biol. d. Pflanzen," Bd. VI., 1893. 

 '^ " Studien an der endotrophen Mycorrhiza von Neottia iiidus-avis,''^ 

 Jahrb. fur IViss. Bol., Bd. XXIV. 



' " Loc. n't. 



