CHANGES IN THE BLOOD. Ill 



greater distance from tlie micrococci the poison becomes more 

 diluted and acts less deleteriously, only producing inflammation 

 and accumulation of leucocytes. Thus it happens that the 

 micrococci are always found in the gangrenous tissue, and that 

 in extending they are preceded by a wall of nuclei, which 

 constantly melts down on the side directed towards them, while 

 on the opposite side it is as constantly renewed by deposition of 

 fresh leucocytes. 



These observations refer to inoculations with fluid containing 

 both micrococci and bacteria, and it might have been supposed 

 that the septicremic bacteria were necessary forerunners of the 

 micrococci, and must to a certain extent prepare the way for 

 them. 



Koch attempted by various means to separate them from each 

 other, but for a long time with no avail. But chance led him 

 to the proper method. A field mouse, which he had already 

 found out possessed an immunity from septicaemia, was inocu- 

 lated with bacteria and chain-like micrococci. The experiment 

 was made in the expectation that neither parasite would 

 develop; This expectation, however, was not fulfilled, for, 

 though the rods, as usual, underwent no development, the 

 micrococci increased and spread in exactly the same manner as 

 had been the case with the domestic mouse. 



Beginning at the point of inoculation in the root of the tail, 

 the gangrene spread onwards along the back, passing deeply 

 among the dorsal muscles, and downward on both sides to the 

 abdominal wall. The animal died three days after inoculation. 

 The parts affected with the gangrene were partially denuded of 

 epidermis and hair, and contained chain-like micrococci in 

 extraordinary numbers. The same micrococci were also found 

 on the surface of the abdominal organs, although there was no 

 visible peritonitis. The blood and the interior of the organs 

 were, on the other hand, quite free from them. From this 

 animal other field mice, and from these again domestic mice in 

 various successive series, were subsequently injected, and with 

 always the like result — namely, that only chain-like micrococci, 

 and in their train progressive gangrene, were obtained. 



The development of bacteria even in a suitable soil can be 

 checked by certain influences, physical, biological, and chemical, 

 and of these none are more potent than temperature. No fully 



