800 JOURNAL OF FORESTRY 



NOT DECOMPOSED IN — 



Rumex acetosa. Vitis vinifera. 



Mahonia aquifolium. Tilia parvifolia. 



Platanus occidentalis. Dierrilla floribunda. 



Prunus laurocerasus. Viburnum opulus. 

 Robinia pseudoasacia. 



Botrytis vulparis, from the above table, has the abiHty to separate 

 the cellulose of the leafy paranchyma of plants of the most diversified 

 families. The variations encountered may be due, in part, to dififerences 

 in nourishment. Behrens infers, from his investigations, that the 

 parasite regulates the development of the cellulose enzyme, when no 

 sugar is present for its nourishment. 



The changes which the extract or poison from the fungus produces 

 in the tissue of the host, are loss of turgor and death of cells, among 

 others through plasmolysis, also separation of cells from each other. 

 That the poison produced is not oxalic acid is evidenced by the fact that 

 oxalic acid, aside from the killing of the cell, creates an entirely differ- 

 ent set of reactions ; and is also poisonous itself to the fungus, in which, 

 no doubt, as in higher plants, its production is self regulated. 



It is often wondered why mosses, which live in a damp atmosphere 

 with little or no air movement, do not mold. This has been previously 

 explained as being due to the "life energy" of mosses ; but the real 

 explanation is that the fungus has no enzyme which can to any extent 

 decompose the cell-membrane and proto-plasm of the mosses. In other 

 words, the fungus is dependent for nourishment upon the cell-sap 

 and this is made available only after the leaf has died. 



Specialization in Botrytis is regulated by moisture in the air and dew 

 which assist in the germination of the spores and the death of plant 

 parts through frost or old age, gives the fungus an opportunity to 

 develop on dead tissue and gain its parasitic attacking strength. 



The author found not less than 84 plants out of 171 immune to 

 infection in the unwounded upper side of the leaf. Of these plants, 

 many' are characterized by a flat, shining, smooth, waxy epidermis; 

 for instance, water plants, as Alisma plantago, Nuphar luteun, and 

 land plants, as Pirus communis, Crataegus oxyacantha, etc. 



The 34 species which proved themselves as susceptible in the un- 

 wounded state as when wounded, had thin epidermal outer walls and no 

 waxy covering so that they offered little mechanical resistance to the 

 attack of the fungus. To these belong the following : 



