300 TEXT-BOOK OF BACTERIOLOGY. 



stray into the different organs by way of the blood-cur- 

 rent. Koch has succeeded in finding- them in the vessels of the 

 brain, liver, and kidneys of a monkey he had killed at the height of 

 the fever attack. 



XIV. PLASMODIUM MALARIA. 



Statements and observations tending- to prove that intermittent 

 fever (malaria) owes its origin to an infectious cause have re- 

 cently been on the increase. 



Such a cause was long since suspected, although malaria is really 

 the most prominent example of a purely miasmatic affection, 

 never appearing (according to all experiences up to the present 

 time) as a really infectious disease and in no case directly transmis- 

 sible from man to man. Epidemiological facts point very emphat- 

 ically to the probability that malaria is, above all, due to very peculiar 

 conditions of the soil. It adhere to deflnites localities with a predi- 

 lection and obstinacy based, of necessity, on extremely intimate 

 relations which are of an almost exclusive importance for the natural 

 conditions of infection. For experimenters have repeatedly suc- 

 ceeded in inoculating previously healthy individuals with the blood 

 of sick persons, and in thus demonstrating that the presumed infec- 

 tious matter actually exists in the blood. 



A large number of investigators (first Laveran, in 1880, and 

 after him Marchiafava, Celli, Golgi, Guarnieri, etc.) have discov- 

 ered a peculiar micro-organism in the blood in nearly all cases of 

 malaria and peculiar to that disease alone. 



This represents an inferior living organism not belonging to the 

 class of bacteria, but to the animal kingdom, to be included~among 

 the protozoa or mycetozoa, and for this reason named by its dis- 

 coverers the Plasmodium malariaB. It appears in the blood 

 within the red blood-corpuscles. 



In the unstained preparation, the hanging blood-drop, and pn 

 the warmed slide table one sees the small, roundish or irregularly- 

 formed structures permeate the body of the cells in which they are 

 domiciled, in a rapid, amoeboid movement. The parasite grows 

 quickly until it almost completely fills the blood-corpuscle. It has, 

 besides, at the same time absorbed the greater part of the haemo- 

 globin and changed it into melanin. While the red blood-corpus- 

 cle fades and becomes more indistinct, there is in the plasmodium 

 an accumulation of numerous roundish granules or rods consisting 

 of the accumulated black pigment. 



The more exact peculiarities of form of this particular micro- 

 organism may be ascertained by staining. Ity taking from the 



