104 MICRO-ORGANISMS AND FERMENTATION. 



like a shell at the circular furrow, and the endosporiuni swells 

 and emerges (/), and elongates itself to a germ tube, which 

 quickly develops conidiophores. 



This fungus very often causes dangerous diseases in wine. It 

 develops freely in casks which have not been carefully cleaned, 

 penetrating into the wood and, in consequence of the decom- 

 position caused by it, producing matter of a disagreeable smell 

 and taste, which subsequently diffuses into the wine. In 

 moist seasons it sometimes covers grapes with a luxuriant 

 growth, giving rise to a peculiar putrefaction. The mycelium 

 seems to penetrate not only into bruised berries, but also 

 into those that are quite sound. These gradually change to 

 a yellow-brown or greenish-yellow, and the fungus produces 

 those well-known putrefaction products which are the cause of 

 the mouldy taste of wine. The conidia of this fungus are 

 also able to germinate in the juice of grapes, on which the 

 mycelium is supposed to exercise a prejudicial influence. 



Penicillium possesses the power of secreting an invertive 

 ferment which is able to convert cane-sugar into other 

 sugars ; it also contains diastase and maltase (BoURQUELOT). 

 This fungus is made use of in the manufacture of Eoquefort 

 cheese. 



WEHMER has described two fungi, Citromyces Pfefferianus 

 and C. glaber, which have nearly the same construction as 

 Penicillium. These form a green covering on suitable nutri- 

 tive media, in which, given a sufficient supply of air and 

 a suitable temperature, they convert the sugar present into 

 citric acid. It is worthy of note that these two fungi are 

 almost insensible to the citric acid accumulating in the 

 nutritive liquid ; indeed, they remain unaffected by even 

 comparatively high concentrations, whilst other acids, and 

 specially mineral acids, even in small quantities, are apt to 

 check their growth. Both of them, according to WEHMER'S 

 statement, are made use of technically in the preparation 

 of this acid. 



A mucor species (M. pyriformis) has also been utilised 

 in this process. 



