ON THE MEDICAL TOPOGRAPHY OF SINGAPORE, 
491 
favor the developement of animal life as warmth and moisture, like¬ 
wise favors the developement of contagion and miasm. Excessive 
cold prevents the developement of contagion, as we see in Polar re¬ 
gions, and high dry heat acts in the same way. “ Meat that would 
putrify in air in 24 hours has been kept without taint tor as many 
days in a vessel containing air previously heated to redness” (Liebig) ; 
in this there is no change in the chemical nature of the atmosphere, 
but the germs of life which are the causes of decomposition are des- 
t roved by the heat. 
Supposing this theory of the vitality of miasm and contagion to be 
sound, we have an extraordinary fact, strikingly noticed in the jun¬ 
gles of America, and in the island of Pinang, easily explained, this 
is, that jungle that was healthy, when cut down becomes for a time 
the scene of malaria, and grounds that were fallow, when turned up, 
give forth miasm and produce fever &c, but after a time will again 
resume their innocuous character. When animal and vegetable mat¬ 
ter is subjected, as in the cutting down of jungle and turning up of 
land, to warmth and moisture, fresh animal and vegetable beings 
are called into existence as the result of decomposition, during which 
state we have malaria active and-producing fever; but, “as it is ob¬ 
served that the infusoria increase in size only to a certain point, it 
must hence be concluded, that their nourishment, even if only from 
the point at which they are to grow, passes out of their bodies in the 
form of excrements, precisely as in the higher order of animals.” As 
it is the case with all other excrements, these must possess, in an 
eminent degree, the property of passing into decay, or petrifaction. 
Hence the increase of numbers of the infusoria must induce and ac¬ 
cumulate the process of putrifaction in the putrify mg body itself, un¬ 
til at last the ultimate products (“ now sensible to our senses and 
ehemical observations”) are eleminated in the shape of carbonic acid, 
ammonia and water, and provided all the get ms are reduced to that 
state, then the malaria ceases to exist and the production of fever is 
stopt. We have already come to the conclusion that there is either 
some malarious influence generated in the fresh water marshes of 
Singapore, which is not in those subject to tidal influence, or, if ge- 
