THE VALUE OF THE TUBERCULIN TEST. 



By \\'. H. Spear, D. V. S., Portland, Me. 



Mr. J. P. Buckley, State Commissioner of Agriculture, has 

 requested me to read a paper on the value of the tuberculin test. 

 In preparing this I felt it would not be out of place to define 

 bacteria and describe briefly the germ theory of disease. 



All soil, air, water and living beings, vegetable and animal, 

 are pervaded with many forms of minute vegetable life. They 

 belong to several distinct classes of families but on account of 

 their microscopic size they are generally grouped under one 

 name as microorganisms. Bacteria, also called microbes and 

 germs, are microscopic plants consisting of single cells con- 

 taining protoplasm, the vital substance by which the processes of 

 nutrition, secretion and tissue building are utilized ; and they 

 reproduce themselves by the division of the parent cell into 

 two smaller cells, the process being constantly repeated. Under 

 the more favorable conditions they multiply with great rapidity 

 and a bacterium may develop and be ready to reproduce itself 

 in a few minutes. In milk, germs seem to find ideal conditions, 

 over two hundred distinct types of harmless and harmful 

 bacteria having already been found in its products, old and new, 

 up to the present time. They are at present provisionally 

 divided into groups based mainly upon their form. The prin- 

 cipal groups are the globe, or round cell shaped bacteria 

 (micrococcus), the rod shaped bacteria fbacillus) and the spiral 

 or corkscrew bacteria (spirillus), and each of these has many 

 hundred species. Warmth, moisture and organic matter favor 

 bacteria growth, while sunlight, the best of all disinfectants, 

 and low temperatures retard them. Some species are readily 

 destroyed, others are very resistant, even to extreme degrees of 

 heat and cold. Disease is often the result of the growth of 

 bacteria in the bodily tissues, and the pathogenic (disease-pro- 

 ducing) germs are mainly micrococci and bacilli. The product 



