330 



BACTERIAL FERMENTATION IN THE INTESTINES. 



chemical changes in the matters containing them. As for their growth and 

 metabolism, they abstract certain substances from the nutritive fluid in which 

 they live, they decompose the chemicals contained therein. In this process 

 some of them form certain substances that may subsequently act as ferments 

 upon matters in the nutritive fluid. 



The microbes are destroyed by antiseptics, such as carbolic acid, salicylic 

 acid, etc., although the ferments are not destroyed. Therefore, these substances 

 afford a means of distinguishing and separating the fermentative from the micro- 

 biotic decompositions. 



The bacteria consist of a capsule and protoplasmic contents. Some possess 

 flagella as organs of locomotion, which, perhaps, are possessed by all capable 

 of motion. The organisms multiplying by division are sometimes collected 

 together in extensive colonies, united by a gelatinous mass, often visible to the 

 naked eye, and which are designated zoogleae. These appear in the form of 

 nodules, branches, patches, flakes, layers of mold, or ropy, creamy or greasy 

 deposits. In the case of some micro-organisms, principally bacteria, multiplica- 

 tion takes place by spore-formation, especially if the nutritive fluid becomes 

 deficient in nutrient material. The rods then grow into threads of considerable 

 size, which become jointed; and globular, strongly refractive granules, from i to 2 /u 

 in size, develop in the individual parts (Fig. 122, 8, 9). In the case of some, as 



FIG. 122. A, bacterium aceti, in the form of cocci (i), diplococci (2), short bacilli (3), and jointed threads (4, 5). 

 B, bacillus butyricus: i, isolated spore; 2, 3, 4, germinating stage of the spore; 5, 6, short and long bacilli; 

 7, 8, 9, spore-formation in the bacteria. 



the butyric-acid germ, the bacilli, before spore-formation, acquire the shape of 

 an enlarged spindle, within which the spores form. After death of the mother- 

 cells, the spores become free, and from them, transplanted to a suitable soil, 

 the newly formed cells of the microbes again germinate. The processes of spore- 

 formation (7, 8, 9) and of germination of the butyric-acid micro-organism (1,2, 

 3, 4) are illustrated in Fig. 122, B. The spores are extremely resistant, being 

 capable, in the dry state, of surviving for a long time, and some even withstanding 

 boiling. 



Among bacteria, a distinction is made between those that exhibit their vital 

 activity in the presence of oxygen, aerobes, and others that thrive only when 

 oxygen is excluded, anaerobes. In accordance with the products to which they 

 give rise by decomposition in their nutrient media, they may be divided into 

 those that induce decomposition in the form of fermentations (zymogenic schizo- 

 mycetes) , those that form pigments (chromogenic) , those that generate bad 

 odors, as in the putrefactive processes (bromogenic) , and, finally, those that, 

 developing in the living tissues of other organisms, cause morbid conditions, 

 even death itself (pathogenic) . Some also elaborate poisons (toxicogenic) . All 

 of these have been found in and upon the human body. 



If it be borne in mind that a large number of bacteria are introduced into 

 the alimentary canal with foods and drinks, as well as, in part, also with the in- 

 spired air; that, further, the temperature of the intestine is especially favorable 



