Bacteriology

                                 

 A few days ago mosquitoes, flies, ticks and related biting and blood sucking insects were considered by most of the people to be unworthy objects of serious study, but now it is known that they are the most important factors in the spread of diseases, especially in tropical countries.

 It has been established by many investigators that these creatures are the sole agents of inoculation into man of the germs of malaria, yellow fever, sleeping sickness, plague, typhus fever, recurrent fever and other maladies which have brought suffering and death to millions of people.

In most cases, they are not merely mechanical bearers of disease germs from one victim to another, for if that were so the problem of discovering the part they would play would be relatively simple.
Usually, their bodies are breeding places of micro-organisms which they suck from the blood of one victim beast or man and these parasites are afterwards injected into their victims. Insects have thus been shown to be intimately related to the life of man and a branch of study which was formerly considered to be purely of zoological interest has proved to be closely connected with the practical problems of finding the cause and the cure of several human diseases. This branch of study is known as bacteriology.