48 TRANSACTIONS OF THE [Sess. lxxxiv 



decidedly conical, solitaiy, and have been found on both 

 surfaces of the leaf, but usually on the upper surface and 

 on the younger parts of the one-year-old stems. 



The external wall of the pycnidium is everywhere 

 several cells in thickness; these cells are more or less hyaline, 

 and are tinged wath gi'een below, but are more opaque and 

 darker in colour towards the upper part of the pycnidium 

 where the wall is considerably thicker. The ostiolar 

 passage is comparativeh^ wide, and although the spores 

 often emerge in the form of tendril-like- masses, they 

 frequently form rounded drops at the mouth of the 

 pycnidium. 



The A-spores vary considerably in shape and size. 

 When a mature pycnidium (i.e. one from which the spores 

 will exude naturally if kept sufficiently damp) is crushed 

 most of the spores are found detached from the sporophores, 

 and the latter form a distinct zone in contact with the wall 

 of the pycnidium. Many of the sporophores appear to be 

 partly disintegrated. The spores can be roughly divided 

 into three groups, as follows: — (1) A few of small size 

 (5'5 X 2-5 ^), which stain readily, and are still attached to 

 the sporophores ; (2) a large number, free from the sporo- 

 phores, which have attained their full length (Q'o-Sju), 

 but which are comparatively narrow (2-5 /a wide), and 

 which still stain readily ; (3) a considerable number, free 

 from the sporophores, which are mature and have attained 

 their full size (6- 5-8-5 x 3-4 //), in which the wall is 

 slightly thicker, and which do not stain readily. Spores 

 which naturally exude from the pycnidium are similar to 

 those of the third group ; they are not accompanied by the 

 sporophores, for these remain inside the pycnidium attached 

 to its walls. The spores are without oil-drops, but often 

 have a minute gi'anule towards one or both ends. 



The B-spores are unusually short compared to those of 

 other species of Phomopsis,^ but show the characteristic 

 arrangement parallel to each other " in serried ranks " 

 when they emerge from a crushed pycnidium. They are 

 easily detached from the sporophores, which, as in the case 

 of the A-.spores, remain attached to the walls of the 

 pycnidium. 

 ' See Grove, The British Species of Phomopsis, Kew Bull., 1917, p. 49. 



