HISTORY OF BACTERIOLOGY 113 



govern all those who set out on the search for the 

 germ of any particular disease: 



First, the germ found in any disease must be found identifying 

 in every case of that disease. Germs 6 



Second, this germ must be grown artificially out- 

 side the diseased body. 



Third, this artificial culture must produce the spe- 

 cific disease in the body of a healthy animal when in- 

 oculated into it. 



Fourth, the same species found in the original case 

 must be found in the case due to inoculation. 



The discovery of the bacillus of Tuberculosis, of 

 Asiatic Cholera, and of Typhoid Fever followed in 

 rapid succession. The last fifteen years have been 

 crowded with searching investigations and numerous 

 brilliant discoveries. 



The debt of the world to these discoverers is in im- 

 portance second only to that which it owes to the bac- 

 teria, the molds, and the yeasts. Because the micro- 

 organisms have been studied so much from the stand- 

 point of disease, both in food substances and man, their 

 beneficent role is often unappreciated. 



From the preceding pages may be gathered suffi- 

 cient information to increase the appreciation of the 

 housewife for her many friends among these micro- 

 scopic plants bacteria, molds, yeasts and to put her 

 on her guard against the many that under certain con- 

 ditions, which she can largely control, will spoil her 



