640 VITAL ACTIONS OF THE LOWER FUNGI. 



are produced. They do not show any very great para- 

 sitic energy, because, as a rule, they are only found in a 

 living state at the margin of the erysipelas, and appa- 

 rently very readily succumb to the influence of the living 

 tissue cells which accumulate there. 

 Penetration Lastly, those species of bacteria which cause the 



into, and . 



multiplication numerous forms of septicaemia and pyaemia which have 

 blood-vessels. ^ een c l se ly studied in animals, live and act chiefly in 

 the blood-vessels. They multiply most readily and 

 rapidly in the free blood current ; they are found espe- 

 cially in the smaller vessels and in the capillaries in 

 such numbers that the vessels are here and there com- 

 pletely filled with them, or the blood corpuscles appear 

 embedded in a large mass of bacteria. They form a 

 thick layer on the walls of the vessels, and their distri- 

 bution is so extensive that, on making sections from any 

 internal organ, almost all the capillaries in every pre- 

 paration are found completely lined by them. Many 

 bacteria also attack the colourless blood corpuscles ; in 

 preparations of such blood large plasma cells are found, 

 which are quite filled with bacteria, others are met with 

 in the stage of decay, which has evidently been caused 

 by the entrance of the bacteria (as in the so-called mouse 

 septicaemia, p. 310). As the result of this extensive 

 distribution of the bacteria serious alterations must occur 

 in the tissue change of all the tissues involved ; the energy 

 of the nutrient stream which passes into the tissues 

 from the capillaries, the removal of the waste products 

 formed in the tissue cells, and the exchange of gases in 

 the tissue, must all undergo a marked alteration ; in 

 correspondence with the altered nutrition of the cells 

 there is an alteration in their functional activity, in the 

 first place, in that more extensive decomposition of the 

 material which is present occurs, for which, on the other 

 hand, there is no corresponding substitute ; in like 

 manner the new formation of cells, in place of those 

 which are exhausted or dead, does not occur in a normal 

 manner. Finally, in addition, we have perhaps also the 

 production of specific noxious materials on the part of 

 the prowino- bacteria, and thus there results a complete 



