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Berkeley states in the ' Gardener's Chronicle,' this parasite was disco- 

 vered by Dr Kayer on potatoes during, or immediately after, the pro- 

 cess of germination. Dr. Montagne, of Lisle, considers this as a new 

 genus between, or allied to, Sepedonium and Asterophora, two genera 

 of fungi which are parasitic within or upon other fungi, e. g. Agarics 

 and Boleti ; it is said to be furnished with bristly spores, whilst those 

 of Sepedonium are echinulate, and those of Asterophora, as the name 

 implies, star-shaped. Dr. Montagne proposes to name this parasite 

 Arlotrogus hydnosporus. 



I have carefully examined many samples of unsound potatoes, and 

 have not succeeded in detecting this fungus. There can be no doubt 

 of its existence; such observers as the Rev. Mr. Berkeley and D. 

 Montagne cannot be mistaken; but the question which suggests itself 

 to my mind is this, — Is the Arlotrogus hydnosporus invariably present 

 in the diseased potato ? I think I scarcely should have failed to 

 detect it if it was. I have been shown what some supposed to be 

 spores of fungi in the intercellular spaces, but these turned out to be 

 the crystalline brownish bodies before noticed, which I conclude to be 

 the remains of the decomposed starch corpuscles. 



Mr. Berkeley states he finds the spawn very evident in the diseased 

 cells when there was no external symptom of the presence of mould. 

 This, then, was the spawn of the Botrytis infestans, and not of the 

 Arlotrogus. Admitting the destruction to be caused by the immediate 

 agency of mucose fungi, which is the destructive parasite .'' — the Fu- 

 sisporium Solani, to which many continental botanists attribute the 

 death of the stem and leaves ; the Arlotrogus hydnosporus of Mon- 

 tagne, which spreads its mycelia through the intercellular spaces of 

 the substance of the tubers ; or the Botrytis infestans, the spawn of 

 which Mr. Berkeley has abundantly detected in the cells of the tubers 

 likewise, and as I am informed by a friend, bursting thi'ough the sto- 

 mata of the leaves, just as Cylindrospora major is figured issuing from 

 the stomata of Tussilago Petasites by Nees and Henry, ' System der 

 Pibse. tab. i. fig. 2. It is considered unphilosophical to ascribe one 

 effect to the operation of several causes, when one would suffice for its 

 explanation, and I suppose the potato-murrain will scarcely be attri- 

 buted to the combined operation of these fungi. Mr. Berkeley says 

 he is convinced the spots upon the tubers arise from the attack of the 

 mould, and that the mould {Botrytis) is not an after organization. 

 No opinion advanced by this accurate observer and profound Myco- 

 logist can be lightly controverted, but other writers attribute the 

 destruction to other fungi, which beyond all doubt certainly exist in 



