SCIENTIFIC COMMITTEE, APEIL 8. 



xlv 



the " Panama Pear." The fungus was determined by Dr. Cooke to be 

 Schizophyllum commune. 



Pitcher on Leaf of Pelargonium. — Mr. Cooper sent a specimen 

 showing a funnel-shaped leafy cup in place of the inflorescence (see 

 Vegetable Teratology, p. 313, for a similar production on the leaf of a 

 Lettuce). 



Scientific Commitee, Apkil 8, 1902. 

 Dr. M. C Cooke in the Chair, and sixteen members present. 



Violet-leaf Disease. — Dr. Cooke reported as follows on some specimens 

 sent by Col. Spragge : — 



" Many of the leaves were in a bad state, the tissue being entirely 

 bleached and dead, but not in interfoliary spots, as in Phyllosticta and 

 Septoria, but marginal, extending inwards until the greater part or the 

 whole of the leaf is involved. It was the opinion of some of the members 

 of the committee that this bleaching was the result of external circum- 

 stances, and not from the attacks of any parasite. With this view I am 

 disposed to agree. The mode of attack is not that of the American 

 disease (Alternaria), of which I have failed to find a single spore. 



" All the spots were occupied by tufts of a black mould, which at 

 present I am inclined to think must be saprophytic, appearing subse- 

 quently on the dead tissue. They do not appear upon the leaves 

 beginning to fade, only on the quite dead spots. These moulds are of 

 two kinds, and both belong to genera of which the species are wholly 

 saprophytic, it being the exception, in some few cases, for them to become 

 parasitic. 



" The fungus appears in small dark olive-coloured tufts scattered 

 over the dead tissue, and in no case becoming confluent, and spreading in 

 patches; 



" The earliest form to appear is a Cladosporium, which certainly is not 

 Cladosporium herbarum, nor does it appear to be Cladosporium epipliyllum. 

 The threads are slender, unbranched, septate, and of a pale olive, 

 not nodulose or torulose, and rather long for the genus (120 to 150 by 5 p). 

 The conidia, as usual, are at first continuous, afterwards uniseptate, then 

 biseptate and triseptate ; so that in the same tuft one may find conidia 

 with no septum, and others with one, two, or three, in all cases narrow, 

 and but little thicker than the threads (18 to 30 by 6 to 7 //). 



" The other form, which appears mixed with the foregoing, is a 

 Macrosporium of the type of M. sarcinula, with delicate deciduous threads 

 and somewhat cubical conidia (30 to 35 by 25 to 30/0, truncate at the 

 ends, and but slightly constricted. The septa, longitudinal and transverse, 

 divide the conidia into quadrangular cells, mostly in three irregular rows, 

 and of a darker olive-brown than appears in the Cladosporium. 



" Unfortunately, I have not seen a description of the Italian Macro- 

 sporium Vwlce, which has the reputation of being a destructive parasite 

 on Violets. 



" It has been demonstrated that there is some close affinity, or rela- 

 tionship, between Cladosporium and Macrosporium. They are often 



