AND PREVENTION OF MALARIA. 239 



muddy wet lands present it in every drop of water ; whilst 

 in our high hills, purified by barrenness and disinfecting 

 peat, we have hunger and health. I do not say that 

 there is a necessary connection between malaria and ani-' 

 malcules, but as there is a connection between them and 

 the state of the air in our own countjr, it is probable that the 

 inquiry may be extended profitably to malarious districts. 

 Infusoria and even larger animals indicate the presence of 

 matter which may putref}^, but it is even probable that 

 they may prevent its injurious action on the atmosphere. 



The microscope then may very soon be brought forward 

 as an instrument for ascertaining the sanitary condition of 

 a country. It is extremely probable that the quality of 

 the decompositions will be known by the microscope to a 

 large extent, and the nature of the disease and its extent 

 be indicated. It was not my intention to have brought 

 forward these views until I had examined in detail this 

 part of the subject, but I fear I shall not soon have an 

 opportunity of doing so, although I have more materials 

 ready than I can find room for in this paper, which is 

 chiefly a practical one. I may readily be misunderstood. 

 I do not say that where most animalcales are there is 

 most disease. Water may exist too putrid for them, and 

 some states of decomposition destroy them. 



It may be said that it was well known that places con- 

 taining less organic matter were less liable to disease, and 

 that the sea coast and barren hills have long on that 

 account been frequented ; but to me at least the reasoning 

 generally and the mode of observing is new, and I feel as 

 if new eyes were given us for observing the soil more 

 minutely. To some extent we can at once tell the quality 

 of waters by the use of the microscope, and have even a 

 clue to the gases and vapours rising. If these waters are 

 taken from the surface of land we have a clue at once to 

 the condition of the land. 



