Marshall Ward.— On a lily -disease. 365 
and collapse, the protoplasm shrinking and turning brown ; and 
these destructive processes extend in advance of the hyphae. 
From all the facts De Bary concluded that the organs of 
attachment excrete a substance which poisons the cells ; the 
latter then collapse, and their expressed sap then serves as 
food for the mycelium, which thereupon sends branches 
further into the tissues, the whole process becoming more and 
more active pari passu. 
Having concluded that a diffusible substance is excreted by 
the fungus, De Bary then examined the juices expressed from 
his rotted carrots ; and he found that pieces of the internodes 
of the bean, or of fresh carrot, or of seedlings of Brassica , if 
put into this juice, underwent strongly marked destruction in 
a few hours. This destruction consisted in plasmolysis of the 
cells ; followed by a slight swelling of the cellulose-walls, and 
finally the dissolution of the middle lamellae. 
To make a long story short, De Bary found that the ex- 
pressed sap of the carrot, after destruction by the Peziza , 
contained a substance or substances which swell cell-walls and 
kill the tissues. From various experiments, and from the 
fact that the sap loses these properties on being boiled, it is 
concluded that the sap contains one or more ferments or 
enzymes, which cause the changes in question. This was still 
more clearly proved by using the fluid expressed from the 
sclerotia : this fluid was strongly active in dissolving the cell- 
walls. 
Then follow experiments on a large scale to prove that the 
infection takes place from plant to plant by means of creeping 
mycelia, which produce organs of attachment on contact with 
the epidermis, and these act in the way described. 
De Bary then points out that this Peziza attacks kidney- 
beans, Petunias, Zinnias, sunflowers, and some other Com- 
posite, carrots, turnips, and occasionally potatoes. 
The parasitism is very remarkable ; while one of two species 
closely allied will resist attack, plants of very distant alliances 
will suffer. Moreover there are some curious cases of local 
and individual predisposition to attack, which are discussed. 
