8 MICRO-ORGANISMS AND FERMENTATION. 



Another kind of moist chamber, invented by Bottcher, 

 consists of a glass ring cemented to a common object-glass, 

 upon which, within the ring, some drops of water are placed. 

 A cover-glass, on the under side of which a small drop of 

 nutritive liquid containing the organisms has been placed, is 

 fastened to the edge of the glass ring by means of vaseline. 



This apparatus is brought under the microscope, and the 

 changes of the organisms are observed from time to time ; or 

 it may be placed in an incubator, maintained at a suitable, 

 constant temperature, and withdrawn at intervals for a 

 thorough microscopical examination. 



These forms of apparatus are adapted to morphological or 

 botanical examinations under the microscope. If, on the other 

 hand, a physiological examination is to be carried out, it is 



FIG. 2. 



Bottcher's Moist Chamber : a, thin cover-glass ; b, layer of nutritive material ; 

 c, glass-ring ; d, liquid. 



necessary that the pure cultures should be developed on an 

 extensive scale. Among the investigators who have developed 

 the methods in this direction, Pasteur, Lister, Koch, and 

 Hansen, deserve special mention. (See " Preparation of the 

 Pure Culture," p. 22.) 



Every fermentation, no matter whether the product be 

 beer, wine, spirit, vinegar, or other liquid, is caused by a 

 vegetation of living organisms, " organised ferments," and, in 

 practice, it is endeavoured to obtain, as far as actual circum- 

 stances will permit, a pure culture of the forms best suited 

 to the manufacture. Although, in our time, with a better 

 understanding of aims and means, great progress has been 

 made in this direction, yet there must always be limits which, 

 from purely practical reasons, cannot be overstepped; the 

 cultures in the factories will never reach such a perfection 



