A CHAPTER ON INSECTS 133 



His observations afford a typical example of the 

 method of zoological research a combination of 

 observation, of experiment and of discerning deduc- 

 tion derived from the results of the complex and 

 involved relations. Several steps were necessary to 

 reach the final conclusion: 



1. The discovery of the micro-organism in man by 

 Laveran in 1880. 



2. Tracing the life history of this germ showing 

 that only a part of its life cycle is carried on in the 

 human body and that another part is in the body of 

 the Anopheles mosquito. 



3. Demonstrating that the bites of an infected 

 Anopheles mosquito transmits the disease. 



4. Camp experiments showing that it is not due to 

 other causes. 



Malaria cannot be contracted by contact with an 

 infected patient, nor through the inhalation of va- 

 pors of swamps. The question now arises, how does 

 a mosquito become infected? When a mosquito 

 sucks blood from a person suffering from malarial 

 fever it draws into its body blood containing the 

 parasite (the second variety mentioned that repro- 

 duce by fertilization) some of which are in a con- 

 dition to conjugate. These forms conjugate and 



