10() MASSACHUSETTS HORTICULTURAL SOCIETY. 



and the action of these onght to tlirow some light upon the 

 doubtful history of the fungus. Some have confidently asserted 

 its connection Avitli the Sclerotinia libertiana, which also occurs 

 in forcing houses, and we should expect that if it does develop 

 an ascosporous form it Avould be of the sclerotinia type. But 

 that the connection has been properly established there seems 

 room for doubt, since the sclerotia or the mycelium of the Scle- 

 rotinia libertiana do not develop the conidiophores, nor have the 

 conidia of this ascosporous form been observed except on the 

 evidence of the doubtful connection of the Botrytis vulgaris. 



Tliis would seem to show that the botrytis was at least nearly, 

 if not quite, separated from the sclerotinia form. From present 

 conceptions of the descent of the group of the Ascomycetes 

 we must accept the view that the botrytis at one time had 

 such a form, or that it is descended from some other botrj'tis 

 form possessing a sclerotinia stage, by differentiation in the 

 conidial form only. This it seems to me is a perfectly natural 

 process in the evolution of forms which are restricted for long 

 periods to only one of their phases of development, and it ap- 

 pears probable that it has prevailed to a very great extent in the 

 Hyphomycetes and Sphteropsidea?. 



Several of the form genera which produce the diseases of 

 plants known as leaf-blight and leaf-spot, like Cercosj)ora, Sej)- 

 toria, Phyllosticta, Pltoma, etc., probably contain numbers of 

 species which do not have any complemental perfect or ascos- 

 porous form. It is true that in several cases the perfect form 

 has been pretty certainly determined. We might cite as illus- 

 trations, the black rot of the grape (Carlia hidwellii), straw- 

 berry leaf-blight (SjiJurrella fraffarh'), leaf-spot of the quince and 

 pear (Entomosporium macxlatum), cotton leaf-blight {Cercospora 

 gossypina), etc. 



The perfect stage of the black rot fungus has been rarely 

 found, and then on dead parts of the grape, as the dead berries 

 which lie on the ground during the winter. The phyllosticta 

 form, which attacks the living leaf, stem, and fruit, and becomes 

 a true parasitic form, is very Avide spread and common. Quite 

 likely it does not need the perfect form as a means for its per- 

 ])etuation, since the leaf-spot usually begins earlier in the spring 

 than the development of the ascosporous form, the pycuospores 

 being able to live through the winter, probably in protected 



