CONTAGIOUS DISEASES. 267 



One of the first of these disease-producing germs to be 

 experimented with was the one we see here. (Photograph 

 of bacillus anthrax.) A little beef tea, or other meat solu- 

 tion properly prepared, was put in one of the little glass 

 tubes, boiled, to destroy any form of life it might contain, 

 and then some of these germs from a case of this disease were 

 introduced by means of a fine wire into the meat juice, and 

 the cotton plug placed in the mouth of the tube to prevent 

 the ingress of any other germs. After a few days the meat 

 juice in the tube was found swarming with these deadly 

 bacteria. Then the experiment was carried a step further 

 by taking some of the germs from this meat juice and intro- 

 ducing them into another tube containing meat juice, pre- 

 pared in the same manner that the first tube was, and in a 

 few days this was found swarming with the same form of 

 bacteria. Then some of this second generation was intro- 

 duced into another tube, and so on, until these germs were 

 removed some six or seven or more generations from the 

 original germs taken from the diseased person or animal. 

 Then some of these, by means of a proper instrument, were 

 thrown under the skin of a healthy animal, when it was 

 found these cultivated germs were as potent to produce the 

 disease as were the original ones taken directly from the 

 body of the person or animal suffering or dead with the dis- 

 ease. These experiments were repeated and always with the 

 same result. 



A few years ago Dr. Koch, a German physician, whose 

 name has since become famous, commenced the study of these 

 bacteria and their relation to disease, and one of the first 

 diseases he studied was the one so common all over the 

 world, — consumption. 



By a careful examination of the matter expectorated by 

 patients suffering from this disease, by means of the best 

 microscopes, — and I might say here it is only by the great 

 improvement in microscopic lenses that has been made in 

 the last few years that we are enabled to study these minute 

 bodies with any degree of accuracy at all, — this observer 

 found these expectorations from the lungs filled with the bac- 

 teria or germs seen here on the screen. (Photograph of 

 bacillus tuberculosis.) These are very minute, and appear 



