HISTORICAL. 17 



of microbes. Very minute quantities are injected into the system, and the 

 resulting reaction increases the power referred to. 



Toxins of bacterial origin received the attention of investigators, and 

 antibodies (antitoxins) were extensively discussed as to their possible relation- 

 ship to health and disease. Enzymes, in their relationship to life 

 processes in plants and in animals, were investigated. It is now supposed 

 that soil toxins of plant origin, as well as those of bacterial origin, influence 

 plant growth. Glandular preparations (ductless glands) have been care- 

 fully tested, and several of these are in use. 



As the result of Wright's discovery of the use of bacterial vaccines in 

 increasing the opsonic index, the tuberculin (lymph) of Koch was again 

 tried in the treatment of tuberculosis, apparently with somesuccess. 



It was found that there were many bacteria other than those which 

 caused disease in animals and plants. Some were found to be decidedly 

 beneficial. Bacterial cultures were employed in butter-making (ripening of 

 cream), in cheese-making, in tanning, in paper-making, siloing, etc. Some 

 bacteria are employed to exterminate certain pest animals. A microbic 

 chintz bug exterminator was tried in 1895-97, but it proved a failure. 

 Microbic rat and mice exterminators (azoa, ratite, mouratus, etc.) are now 

 being tested, and they appear to be quite successful, at least in certain 

 localities and under certain conditions. A microbic rabbit exterminator 

 has been tried in Australia. 



In 1879 Dr. Frank, of Berlin, began his investigations of the leguminous 

 root nodule microbes. In 1893 the writer attempted to utilize these microbes 

 in increasing the yield of certain gramineous crops. In 1896 Nobbe and 

 Hiltner, of Germany, introduced a patented microbic fertilizer for legumin- 

 ous plants. In 1907 a California soil microbe was isolated which appears 

 to be especially active in promoting the growth of sugar beets. This experi- 

 ment led to the supposition that perhaps every species of plant has its pecu- 

 liar bacterial flora, symbiotically (mutually beneficent) associated with the 

 root system, mutually essential to active development. The importance of 

 soil bacteria in setting free plant foods has been demonstrated by numerous 

 investigators of Europe and of the United States. Yeast and mould organ- 

 isms are practically utilized in the manufacture of beer, sakd, and other 

 food and drink products. 



The above condensed outline of the history of bacteriology may be 

 summed up as follows: 



1. Ancient conceptions of disease and of spontaneous generation, dating 

 back to 500 years B. C. 



2. Discovery of micro-organisms about 1660 by Leeuwenhoek, followed 

 by the work of Robert Hooke and a few others. 



3. Discovery of bacteria in air, dust, and decaying substances, and the 



