36 MICROBES AND THE MICROBE -KILLER. 



first little red spots became visible. These gradually yet 

 rapidly grew larger and spread until they covered the 

 leaves and extended to the fruit, and in about three 

 weeks it was possible to determine how the crop would 

 be affected. Having used so many medicines and drugs 

 on myself, there were almost the contents of a drug 

 store accumulated in my laboratory, and so, with the 

 help of my garden books and a small microscope, I set 

 to work to investigate the matter more closely. First 

 of all I examined about forty varieties of grapes that 

 were at my disposal. Some of them were more infested 

 than others. Several were not attacked at all, and 

 others very slightly, so that they soon recovered and 

 lost all evidence of disease. Among those least diseased 

 were the Delawares, Concords, and a few others, and 

 these I could always depend upon ; but the Black Span- 

 ish, Tokay, and all the California varieties were easy 

 victims to the fungus. There was abundant material 

 upon which to experiment, and I began with all the 

 remedies that had been suggested by the Agricultural 

 Department at Washington in the articles published 

 from that office on the diseases of the vine, but with 

 little or no effect. If I used the drugs sparingly they 

 failed to destroy the fungus, and if I used them more 

 liberally they killed the vine, or, at the best, they de- 

 stroyed the fruit and the leaves. I found prevention to 

 be better than cure, and that the disease was kept away 

 either by putting a roof over the vine or covering the 

 grapes with a paper bag, thus warding off rain and dew. 

 Noting the temperature and condition of the atmosphere, 

 and the effects of sudden changes of the weather on my 

 vines, I observed that when these were greatest there 

 was also more coughing and more sickness among the 

 people. Common-sense, and no great exercise of reason, 

 led me to see that the same causes had opei^ated in both 

 cases, and that the human race suffered from the same 

 influences as those which brought disease to the plants 

 and to the vegetable world. All organic life is, in fact, 

 affected in the same way; and although it has frequently 



