162 BACTERIA. FUNGI. 



The process gives the impression of being a repeated splitting of the cells, and 

 this is the origin of the name of Fission-fungi (Schizomycetes) used to designate 

 these organisms. It has been observed that within 20 minutes a bacterium-cell 

 grows enough to be able to divide or split into two, and hence it has been calculated 

 that from a single cell, under favourable external conditions, upwards of 16 millions 

 of similar cells are produced in 8 hours; and in 24 hours many millions of millions. 



It is this very capacity for rapid multiplication that gives so great an impor- 

 tance to Bacteria as parasites. For multiplication can only take place at the 

 expense of the juices and nutrient substratum in which they live. If this nutrient 

 substratum is to afford materials for constructing the millions of millions of cells 

 produced within two periods of 24 hours, a far-reaching transformation is inevitable. 

 Now, for certain bacteria, the blood, with its albuminoid compounds and carbo- 

 hydrates, is an extremely favourable medium of nutrition; moreover, the tempera- 

 ture of the blood of men and other mammals (35°-37°C.) could not be more 

 suitable for the development of bacteria. Hence, it is readily intelligible that if a 

 single parasitic bacterium-cell gets into the blood, it may be the origin of innumer- 

 able other cells, and that these are in a position, in a comparatively short time, to 

 alter and decompose the whole mass of the blood. Owing to their extraordinary 

 minuteness, bacteria are able to penetrate from outside into the channels of the 

 blood by a number of spots: every abrasion, pin-prick, and sore place, may become 

 an entrance-door: so, too, through all the external orifices of the various canals in 

 in the bodies of men and animals, the bacteria can enter, especially, through the 

 passages to the respiratory organs — and it becomes more and more probable that 

 bacteria, diffused in the air, are in the main introduced into the respiratory organs 

 by the process of breathing, thence penetrating into the finest blood-vessels, the so- 

 called capillaries, and so pass into the current of the blood. 



As regards the parasitic action of bacteria when they have penetrated into the 

 bodies of men and animals, the supposition is that the protoplasm of each bacterium 

 works as a ferment upon the environment, splitting up the chemical compounds in 

 immediate proximity to it, and attracting and incorporating such products of the 

 decomposition as are necessary for its own growth. Parasites with this method of 

 operation act, at all events, much more destructively than those which, although 

 they too absorb part of the host's juices, yet do not enter upon the necessary 

 decompositions until the juices have passed into the cavities of their own bodies, 

 and, therefore, do not alter the constitution of the unabsorbed residue. When the 

 component parts of the blood are split up and resolved by bacteria, the nutrition of 

 the host must be especially disturbed, and so must all the functions of the organs 

 through which the blood perpetually circulates. Ultimately it may culminate in 

 the organs ceasing to exercise their functions, and in the death of the host. When 

 one remembers how fast the blood is pumped by the heart's action into every part 

 of the body, it becomes intelligible how bacteria, possessing the power of decom- 

 posing the blood, may also cause the death of the host at very short notice, as we 

 have occasion to observe whenever there is an epidemic of cholera. 



