Roberton. — Malaria and Mosquitos. 229 



successfully with the disease. " So long as its cause was 

 unknown the methods of treatment were empirical, and so 

 long as there was no definite notion of the mode in which 

 it was disseminated efforts to prevent it were imperfect and 

 to a large extent futile." 



The same vagueness which until recently characterized 

 our knowledge of malaria w T as characteristic also of many 

 fevers, but the number of these has been much reduced during 

 the latter half of the nineteenth century, owing to the birth 

 of what is known as the "germ theory." It was shown that 

 some diseases were due to the presence in the body of certain 

 small organisms or germs. The importance of this discovery 

 was so great that, as is often the case under similar circum- 

 stances, there was a tendency to explain the origin of pretty 

 well all diseases by the " germ theory." Investigators setting, 

 to work at some disease with this as a working hypothesis 

 easily persuaded themselves that some germ they had found 

 was the cause of the disease. In some instances these dis- 

 coveries were confirmed, but in numerous other cases it was 

 shown that the enthusiasm of investigators had led them 

 astray. Malaria was one of the diseases which certain observers 

 were prepared to ascribe to bacilli they had discovered in 

 malarial patients, but these observations were not confirmed. 



There were so many false hopes raised in this way that 

 the announcement of a new discovery of the kind was at last 

 regarded with great suspicion, and when it was reported that 

 a French military surgeon in Algiers, named Laverau, had 

 found certain peculiar bodies present in the blood of malarial 

 patients, and in the blood-cells of malarial patients alone, his 

 opinion that they were the essential cause of malaria was not 

 much regarded. His work, however, stood the test of time, 

 and after many years was confirmed by other scientists, and 

 received recognition at the hands of even those who had pre- 

 viously thought they had reason to think a bacillus respon- 

 sible for the disease. These bodies found by Laverau were 

 not bacteria. They were more closely allied to the group of 

 low organisms called Coccidia. These bodies are very insig- 

 nificant, but it was noticed that they underwent growth and 

 other changes in the blood-cells, the last stage consisting in 

 their rupture and the liberation of spores, which serve to 

 begin another cycle. It is interesting to note that this cycle 

 corresponds in length of time with the period from the begin- 

 ning of one attack of fever until the beginning of the next. It 

 was shown also that there were different varieties of parasite, 

 some taking longer than others to go through the cycle. 

 This corresponded with what was already known about 

 malarial fevers — that one kind took two days, another three, 

 from the beginning of one attack to the beginning of another. 



