1 86 THE POPULAR SCIENCE MONTHLY 



BACTERIOLOGY AND PARASITOLOGY IN RELATION TO 



AVIAN DISEASES 



By GEO. EDWARD GAGE, Ph.D. 



MARYLAND AGRICULTURAL EXPERIMENT STATION 



DURING the last ten years the sciences of bacteriology and para- 

 sitology have been established beyond previous expectation. 

 To-day these sciences are so far-reaching that they not only have to do 

 with medicine but extend into the realm of hygiene, agricultural sci- 

 ences and the industrial arts. The advances made in connection with 

 the life histories of the various microscopic animal parasites and the 

 studies which have led to a general understanding of the relation 

 between parasite and host have done much toward unearthing mysteries 

 of diseases which attack domestic fowls and menace the poultry in- 

 dustry. Bacteriologists have enabled the avian pathologist to study 

 and control these fatal diseases. 



Practical applications of bacteriology to the arts and industries are 

 only instances of the ramification of this science. In agriculture and 

 closely allied science, bacteriology and also parasitology have been 

 immediately and intelligently employed to set forth new facts and 

 expose new problems. During the last few years bacteriology has held 

 close relations with medical science. By the application and extension 

 into the field of protozoon pathology one of the latest and most helpful 

 developments in the study of infectious diseases has evolved. This is 

 not alone true of human pathology, but must include avian, insect (such 

 as bee and silkworm), sheep, swine and cattle diseases and possibly the 

 diseases of plants. 



In the poultry yards epidemics of the so-called " white diarrhoea," 

 " black-head " of turkeys, and tape-worms, have demanded scientific 

 study for remedial help. The loss to the poultryman is at present 

 almost incalculable. The etiology of many diseases is understood 

 only by the discovery of some bacteria or parasite. The mode of en- 

 trance of the invading microorganisms to the avian body, the study of 

 the original source of the infectious material and the possibilities of 

 transmission and infection can be apprehended only through prosecu- 

 tion of detailed bacteriological and parasitological studies. Individual 

 birds may suffer from malnutrition and be afflicted with ailments which 

 may be the result of inability to utilize food properly, but when a whole 

 flock becomes droopy, listless and unable to maintain normal life, we 

 must resort to the field of parasitology or bacteriology for the cause. 



