64 



same fungous g^ows on some of our pasture grasses, and often occasions gn:eat 

 mischief to cattle. 



In some parts of France the peasantry do not object to eat mouldy bread, 

 and in most instances \vith impunity, but the species of mould varies, and alarming 

 effects have sometimes followed. These, together with experiments performed on 

 animals, prove that bread in a state of mouldiness wiU cause death. M. Barnil, 

 the French analyst, who reported to his government on these cases, advises "that 

 as most people are unable to distinguish the species of mould, the use of aU bread 

 in such a condition should be avoided." 



Next in importance to corn, as a starch producing vegetable, is the potato. 

 Many funguses attack it. The Peronospora Infestans that is so very destructive 

 is one of the white moulds. The mycelium of this fungus is able to penetrate 

 every part of the i)lant, discolouring and corroding the green parts, and causing 

 loss of vitality and decay in the tuber. Partial observations of several mycologists 

 had revealed much of its life history and mode of growth during the summer, but 

 it was for an honorary member of the Woolhope Club to discover how it survived 

 the winter. It has long been kno\vn that some funguses, like insects, go through 

 several stages or metamorphoses. The final and perfect stage is easily recognised 

 in most insects, because that is the only one that has the power of reproduction, 

 but among funguses every stage is able to propagate itself in some way, thus in 

 summer the potato blight throws off from the free ends of its mycelial threads two 

 kinds of short-lived sjiores, which if they fall on the leaf of a potato, germinate 

 and quickly reproduce themselves, killing their victim and perishing with it. 



Our friend, Worthington Smith, had the good fortune, while investigating 

 the natui'al history of this fungus, to discover another kind of spore, called resting 

 spore, because it hybernates in or on the ground. He watched its mode of forma- 

 tion in the autumn, and its growth the following spring, and then was enabled to 

 prove that this spore was the long sought for means by which Peronospora 

 Infestans continues its existence from year to year. 



This spore is to be found in the tissues of the decaying plant. It is formed 

 by a process of conjugation not uncommon among funguses ; by degrees it acquires 

 a hard protecting coat, and with the dying plant, falls to the ground, where it 

 remains, to take its chance during the winter ; on the return of warmth, 

 the hard coat bursts , mycelial threads exude and extend in search of a foster 

 mother ; if they do not meet with a potato plant in growth, they speedily exhaust 

 themselves and die ; but if unfortunately successful, they pierce the cuticle, and 

 the work of destruction commences. 



Through want of thought and custom, much is done that favours the exist- 

 ence and propagation of this pest, diseased haulm and tubers are left on the surface 

 of the ground, when the crop is taken up, and are afterwards dug in to serve as 

 manure. If this happens in a garden or rented potato ground, and the same crop 

 is put in a second year, a vigorous crop of Peronospora is the result, and the cot- 

 tager scarcely gets his seed back. The potato blight is also extensively propagated 



