THE MICUOBES OF HUMAN' DISEASES. 183 



produced in artificial cultures. It is not found in the 

 healthy parts of Lornbardy. In the strata of air 

 which tloat above malarious ground in summer, this 

 microbe is so common that it is found in abundance 



in the sweat of the forehead and 



hands (Fig. 83). 



This organism is not only 



capable of cultivation, but rabbits 



and dogs can be inoculated with 

 pig. 83. Malaria bacillus ^, so as to produce marsh fever 



in them.* The lesions which 



are observed in an autopsy are the same as those in 

 man, showing that the site preferred by the microbe is 

 the spleen and the marrow of the bones. 



The fact that the bacillus and its spores are suc- 

 cessively found in the blood explains the intermittent 

 type of the disease, tertian, quartan, etc., according to 

 the variety of marsh fever. According to its variety, 

 and perhaps to the species of Schizophytum, the com- 

 plete evolution of the plant sometimes demands 48, 

 sometimes 72 hours, and the access of fever always 

 corresponds with the period of greatest activity in 

 the bacillus that which precedes the emission of 

 spores. 



Two military surgeons, Laveran and Richard, 



* It is generally believed in France thnt animals, and especially 

 herbivora, cannot contract intermittent lever. This opin.ou is irro- 

 neous. It is known that in Italy cattle contract this fever when they 

 are not acclimatized to uiaibhy districts, and that the} arc cured bj 

 sulphate of tjiiiuiiie. 



