SCLEROTINIA DISEASE OF THE GOOSEBERRY. [APRIL, 



of spores, which give the tufts of the fungus its characteristic 

 fluffy or minutely powdery appearance. Each spore of the 

 fungus, it must be noted, is able, just like the seed of higher 

 plants, to give rise to another distinct individual of the 

 same kind, and thus spreads the disease. 



The fructification shown in Fig. 4 has long been known 

 tinder the name of Botrytis. It has lately been discovered, 

 however, that this is a stage of a fungus called Sclerotinia. 

 Turning to Fig. 1 again, we should find, if we looked care- 

 fully into the cracks of the bark where the Botrytis fructifica- 

 tions are appearing, that while some spring directly from the 

 spawn of the fungus hidden in the tissues of the stem, others 

 arise from small, hard, blackish bodies, a few millimeters 

 long and of irregular shape. These little blackish bodies 

 consist of a dense compact mass of thin-walled, colourless, 

 fungus tissue within ; and on the outside of a protective layer 

 of dark-coloured, thicker-walled cells. Such bodies are called 

 sclerotia; they are extremely resistant to climatic conditions 

 such as frost, drought, etc., and serve to carry the fungus 

 through all vicissitudes from one growing season to the next. 

 In Fig. 5 is given a microphotograph of portions of two 

 sclerotia which have partly grown together; one (to the left) 

 has just commenced to grow again, and to produce a tuft of 

 eonidiophores, the basal portions of which are visible. These 

 sclerotia are able under certain conditions to give rise to 

 another form of fructification in which winter-spores (dsco- 

 spores) are produced. In this stage the fungus has been known 

 under the name of Sclerotinia, while the name Botrytis has 

 been applied to the stage (shown in Figs. 1, 2, 3, 4) where 

 summer-spores only are produced. It is probable that the 

 Sclerotinia stage, with its winter-spores, only rarely occurs. 

 It is certain that the disease can be perpetuated from season 

 to season in its absence by means of the Botrytis stage, which 

 by means of summer-spores spreads the disease during the 

 growing season, and then remains dormant in the form either 

 of mycelium in the stem or of sclerotia on its surface — both 

 enabling the fungus to hibernate during severe winters. I 

 have frequently seen, as early as February, numerous 

 powdery tufts of eonidiophores on the surface of an affected 

 stem ; it is probable that such survive all through mild winters 



