638 



VITAL ACTIONS OF THE LOWER FUNGI. 



ptomaines 

 when they 

 STOW over a 

 large extent 

 of surface. 



Bacteria 

 which act as 

 poisons in 

 smaller num- 

 bers, and 

 which 

 ultimately 

 penetrate 

 into the body. 



Bacteria 

 which readily 

 penetrate into 

 the body, and 

 multiply in its 

 interior. 



Growth in the 

 body accom- 

 panied with 

 necrosis of the 

 tissue 



skin, on the mucous membranes, on wounds, in the in- 

 testine, &c., and cause injury to the body by producing 

 ptomaines which, being soluble, penetrate from the sur- 

 face into the body and there act as poisons. Many of 

 the bacteria belonging to this class live as a rule as 

 saprophytes. Some of them excite fermentation and 

 putrefaction ; they do not injure the living animal at all 

 so long as they occur in small numbers on the surface, 

 and it is only when they can develop in large numbers, 

 and when they are not removed from time to time, as 

 occurs under normal conditions, that the production of 

 ptomaines is so marked that injury to the host ensues. 



Some bacteria have a more marked pathogenic cha- 

 racter, in that they produce very poisonous ptomaines, 

 to which the bodies of warm-blooded animals have not 

 become gradually adapted. Hence these injure the 

 organism, even when they are growing only over a slight 

 extent of surface. It not uncommonly happens in this 

 case that the ptomaine action is only the precursor of the 

 invasion of the bacteria into the interior of the body ; 

 the latter is so weakened by the poisoning that the 

 bacteria find less resistance, and can develop in the 

 blood and in the organs, which previously could easily 

 have resisted their invasion. 



A further stage in the development of parasitismus 

 is represented by those bacteria which, without further 

 assistance, and in relatively small numbers, can establish 

 themselves in the interior of the living body and multiply 

 there. These either lead to local morbid processes 

 (tuberculosis, pneumonia) at the place of entrance, or 

 they spread through the whole body with the circulation, 

 and grow in the whole of the capillary vascular system. 

 The bacteria then occasion either morbid growth of tissue 

 or necrotic destruction of tissue, or the mechanical dis- 

 turbances of the tissue change and of the cell life which 

 results from the distribution and multiplication of the 

 bacteria leads to grave injury to the animal by means 

 again of specific ptomaines. 



The gradual spreading necrosis of the tissue, and the 

 spread of the bacterial growth into new territory killed 



