20 BACTERIA, YEASTS, AND MOLDS 



ture contained the descendants of one organism only. That 

 simple little method revolutionized the study of bacteria 

 and opened up the field to any one who wanted to explore it. 



Some of these new students were French and some were 

 German. The rivalry between the two schools became even 

 more intense as discovery after discovery was made, first 

 in one country and then in the other. It was at its height, 

 perhaps, when diphtheria antitoxin was discovered. Here 

 the honors were very evenly divided. A Frenchman, 

 Emile Roux, first discovered that diphtheria germs pro- 

 duce a poison which we call diphtheria toxin. His work 

 was quickly followed up by Behring, a German, who, 

 by the use of this diphtheria toxin, actually produced 

 antitoxin on a small scale, enough to cure a small animal, 

 but hardly enough to be of practical value to a human 

 being. Then Roux went further and produced it on a 

 practical scale. 



Discoveries came rapidly thereafter. The first bacteria 

 to be studied were naturally those of disease, because 

 every one was afraid of diseases and wanted to see mankind 

 rid of them. But later other kinds of bacteria were given 

 attention. Even before Pasteur's day it had been learned 

 why milk soured ; but now it was learned how to keep it 

 sweet and how to prevent other foods from spoiling. It 

 was found that bacteria are everywhere, and that no 

 household can be run in such a cleanly way as to exclude 

 them. Many of these discoveries have practical value to 

 the housekeeper. Since she has bacteria around her on 

 every hand, since they may be mischievous or may be 

 among her best friends, it behooves her to learn how to 

 keep these invisible members of the household under control. 



