6 Robinson, Puccinia vmlvacearmn and its host plant. 



(t) is situated on a mycelial cushion {c) directly below the 

 epidernriis {ep.), and the mycelium ramifies in the inter- 

 cellular spaces and disorganised tissues of the mesophyll 

 right through to the upper epidermis. At maturity the 

 developing sorus ruptures the epidermis, as in the case of 

 the petiole. These observations confirm the descriptions 

 of Taubenhaus^ and of Werth and Lugwigs," but whilst 



Texl-fg. 4A. Surface view of leaf lamina, showing pustule 

 in relation to several of the finer veins. x 50. 



• B. V.S. of portion of leaf lamina bearing a young 

 pustule and showing the distribution of the fungus 

 in relation to the tissues. x 50. 



the first named states that haustoria are rarely found, I 

 have observed haustoria, in the early stages of infection, 

 in almost every cell of the affected region. 



Text-fig. 5 shows the distribution of the starch in the 

 affected and unaffected parts of a portion of the stem. 



1 "A contribution to our knowledge of the Morphology and Life 

 History of Puccinia vtaivaccartiiii." Phytopaiholfgy, vol. i. 



- " Zur sporenbildung bei Rost und Brandpilzen.'' Bo. d. Deutsche 

 Bot. Ges., Bd. XXX., lit. 8. 



