1 8 Y>V^\Y.\<\.YN, Life-History of Leptosphceria LemanccB. 



if subsequentl)', the spores are usually present in normal 

 abundance. {Text-fig. 4.) 



Infected filaments not infrequently appear to contain 

 an abnormal amount of mucilage, and it is interesting to 

 note that the fungal mycelium aipparentl}' flourishes most 

 vigorously in this substance. The prismatic cortical cells 

 appear to be little affected. In sectional view the differ- 

 ence between healthy and diseased Lemanca shoots is 

 striking. The former shew middle and medullary layer 

 cells, with clearly defined wails, and contents consisting of 

 a large central vacuole, a small amount of protoplasm 

 spread thinly around the periphery, and a large nucleus. 

 The latter contains a large, prominent, compact, centrally 

 pUced and deeply staining nucleolus, which may be homo- 

 geneous, contain one or two vacuoles, or one to four 

 deeply staining granules — " nucleolini." {PL II., Fig. 19.) 

 In diseased tissue mucilaginous degeneration of the walls 

 occurs, and in many cases it is difficult to determine their 

 boundaries. The fungal haustoria not infrequently appear 

 to apply themselves to the nucleus, which loses its ovoidal 

 form. The nucleolus and nuclear membrane disappear 

 and simultaneously the cell protoplasm degenerates. {PL 

 II., Figs. 20 — 22.) No instance has been discovered in 

 which a cell invaded by haustoria has possessed a normal 

 nucleus, and in the majority of cases little or no trace 

 of it remains. Not all the cells which are affected or 

 killed, however, contain haustoria, and on the other hand 

 apparently perfectly normal cells are occasionally present 

 in the midst of affected tissue. 



Systematic Pcsition. 



The correctness of the accepted systematic position 

 of the fungus may be questioned. It is included under 

 Leptost?h(Etia, a genus in the Pleosporaceae (10), (13), (14). 



