230 DR. R. ANGUS SMITH ON THE PRODUCTION 



2. Prevention of Malaria. 



If we can imitate the production of malaria, can we not 

 also imitate the mode by which it is destroyed or prevented I 

 "Wlien the products of decomposition are formed in a soil 

 they are removed by natural processes. Mere mixture with 

 the soil will remove or render decomposing matter innocent. 

 The soil will act as a porous body. But the soil may be 

 overburdened. It may be shallow, and its machinery may 

 be of small force ; or it may be inefficient from the excess 

 of organic matter over the amount of air passed through 

 it. The first act of disinfection is the action of the soil as 

 a porous body. The next seems to be the act of oxidation 

 by which the soil at the surface is rendered acid. By 

 these means decompositions are confined within the soil 

 itself. 



We may consider the atmosphere to be in a constant 

 struggle with the vegetable matter of the soil. Substances 

 containing nitrogen are constantly tending to give out 

 ammonia^ the ground is constantly tending to convert this 

 into nitric acid, whilst it converts other portions into car- 

 bonic and organic acids. By manuring we assist the 

 tendency to become alkaline, taking the side of vegetation, 

 and we resist the oxidising tendency of the air. A large 

 portion of our manuring is simply the addition of alkalies, 

 a struggle against the acidifying influence of the air. No 

 wonder it requires so much lime for the fertilizing of acid 

 peat lands. From lands of this kind it is probable that no 

 miasma arises. 



Moisture lying on rich lands becomes filled with animal 

 and vegetable life, a sure sign of rapid decomposition. 

 Allow this moisture to pass through the soil and this 

 animal life disappears. This is an act of purification by 

 drainage. It may not at all times be possible to obtain the 

 requisite amount of drainage, and there are even cases 

 where the land produces malaria, without, according to the 



