188 THE POPULAR SCIENCE MONTHLY 
body of the bird and consequently eliminate infection. Contributions 
from the Division of Biology of the Rhode Island Experiment Station 
have furnished us interesting facts concerning parasitism of Cytodites 
nudus, a mite and Hemaphysalis chordeilis, a tick and these are but a 
beginning to the study of such parasites affecting birds. It demon- 
strates the field for research in parasitology and what contributions 
from this realm of science would mean in determining the cause of so 
many diseases, the etiology of which at the present time is unknown. 
Fowl typhoid, cholera, tuberculosis and hosts of other afflictions were 
discovered through the aid of scientific bacteriologists. In a very 
recent publication? Professor Rettger, of Yale University, has demon- 
strated the value of bacteriology, by his valuable contribution to the 
study of white diarrhoea. He has been able to demonstrate the role of 
bacteria in the etiology of this disease. We need no better example of 
the usefulness of such a science in planning investigations of this na- 
ture. By thorough bacteriological methods he has been able to give 
us the results of his work and has shown how infection may occur, 
what it means to the poultry industry, and methods of prevention. 
This also demonstrates how bacteriological methods have been used to 
study epidemiology. It has given a procedure based on bacteriological 
facts and with such methods at hand we are supplied with the means 
of suggesting treatments which undoubtedly will do much toward 
solving the problems which have heretofore been unsolved. These 
studies have shown that the function of pure water and food and san- 
itary conditions are essential to the daily life of domestic birds. If 
diseases of the poultry yards are to be suppressed, hygienic measures 
must be observed here as with human beings. It was not until after 
the introduction of hygienic measures such as a proper sewage dis- 
posal, and water filtration that the death rate of typhoid fever was 
perceptibly diminished in this country and Europe. 
Conspicuous as the achievements have been in bacteriology, it can 
not be said that the field is exhausted. There is hardly an infectious 
disease of the poultry yards which does not have to do with some bac- 
terium or parasite, and the variations and adaptations of these patho- 
genic forms is to-day one of the difficult problems with which the avian 
pathologist has to deal. It is for the scientist to determine whether 
certain bacteria and parasites owe their pathogenic action to the organ- 
isms themselves or to their toxic or poisonous by-products. The field 
of immunity as related to avian pathology is unexplored. This would 
be among the most complicated that the scientist could undertake, yet 
the fields of bacteriology and parasitology with its many perfected 
methods of attack would indicate that it is not impossible. Not only 
human medicine, but also veterinary science owe much of their ad- 
2 Bulletin 60, Conn. Agr. Exp. Station. 
