286 



FERMENTATION OF CARBOHYDRATES. 



tissues and partly for their own metabolism. In these processes, some of the substances so 

 absorbed and assimilated undergo chemical changes, soma ferments seem thereby to be produced, 

 which in their turn may act upon material present in the nutritive fluid. 



These fungi consist of a capsule enclosing protoplasmic contents. Many of them are provided 

 with excessively delicate cilia, by means of which they move about. The new organisms, 

 produced by the division of pre-existing ones, sometimes form large colonies visible to the naked 

 eye, the individual fungi being united by a jelly-like mass, the whole constituting zoogloea. 

 In some fungi, reproduction takes place by spores ; more especially when the nutrient fluids are 

 poor in nutritive materials. The bacteria form longer rods or threads, which are jointed, and 

 in each joint or segment small (1-2 fi) highly refractive globules or spores are developed (fig. 

 203, 7). In some cases, as in the butyric acid fermentation, the rods become fusiform before 

 spores are formed. When the envelope of the mother-cell is ruptured or destroyed, the spores 

 are liberated, and if they fall upon or into a suitable medium, they germinate and reproduce 

 organisms similar to those from which they sprang. The process of spore-production is 

 illustrated in fig. 203, 7, 8, 9, and in 1, 2, 3, 4 is shown the process of germination in the 

 butyric acid fungus. The spores are very tenacious of life ; they may be dried, when they 

 resist death for a very long time ; some of them are killed by being boiled. Some fungi exhibit 

 their vital activities only in the presence of (robes), while others require the exclusion of 

 (anaerobes, Pasteur). According to the products of their action, they are classified as follows : 

 Those that produce fermentations (zymogenic schizomycetes) ; those that produce pigments 

 (chromogenic) ; those that produce disagreeable odours, as during putrefaction (bromogenic) ; 



and those that, when introduced 

 into the living tissues of other 

 organisms, produce pathological 

 conditions, and even death 

 (pathogenic). All these dif- 

 ferent kinds occur in the human 

 body. 



When we consider that num- 

 erous fungi are introduced into 

 the intestinal canal with the 

 food and drink that the tem- 

 perature and other conditions 

 within this tube are specially 

 favourable for their develop- 

 ment; that there also they meet 

 with sufficient pabulum for 

 their development and repro- 

 duction we cannot wonder 

 that a rich crop of these organ- 

 isms is met with in the intes- 

 tine, and that they produce 

 there numerous fermentations. 



I. Fermentation of Car- 



X. 



'A 



3%# 



<9\ t 



''\ 



4 



y 



i 



Fig. 203. 

 A, Bacterium aceti in the form of cocci (1) ; diplococci (2) 

 short rods (3) ; and jointed threads (4, 6). Bacillus butyricu 



(1) isolated spore ; (2, 3, 4) germinating condition of the bohydrates (1) Bacil- 

 spores ; (5 6) short and long rods ; (7, 8, 9) formation of lus * idi lactici VonmV* of 

 spores within a cellular fungus. * a . C1Q f ^CUCl consists ot 



biscuit-shaped cells, 1 -5-3 //, 

 in length, arranged in groups or isolated. They split up grape-sugar into lactic 

 acid; 



1 grape-sugar = C 6 H 12 6 = 2(C 3 H 6 3 ) = 2 lactic acid. 



Milk-sugar (C 12 H 22 O n ) can be split up by the same ferment causing it to take up 

 H 2 0, and forming 2 molecules of grape-sugar, 2(C 6 H 12 6 ), which are again split 

 into 4 molecules of lactic acid 4(C 3 H 6 3 ). 



This fungus and its spores occur everywhere in the atmosphere, and are the cause of the spon- 

 taneous acidification and subsequent coagulation of milk ( 230). 



(2) Bacillus butyricus, which in the presence of starch is often coloured blue 

 by iodine, changes lactic acid into butyric acid, together with C0 2 and H (Praz- 

 mowski). 



2(C 3 H 6 3 ) lactic acid 



C 4 H 8 3 = 1 butyric acid. 

 2(C0 2 ) = 2 carbon dioxide. 

 4H = 4 hydrogen. 



