HISTORICAL 1 7 



on the invading bacteria in such a manner as to render them more liable to 

 be attacked and assimilated by the white blood-corpuscles or leucocytes. 

 There are possibly as many opsonins as there are microbes capable of being 

 digested by the leucocytes. The microbe-devouring power of the leuco- 

 cytes can be increased by the use of bacterial vaccines, which consist of 

 suspensions 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 rela- 

 tionship 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 plan t 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 some success. 



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 mi- 

 crobic chintz bug exterminator was tried in 189-^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 succesful, 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 mi- 

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

 ->and Hiltner, of Germany, introduced a patented microbic fertilizer for 

 leguminous plants. In 1907 a California soil microbe was isolated which 

 appears to be especially active in promoting the growth of sugar beets. 

 This experiment led to the supposition that perhaps every species of plant 

 has its peculiar bacterial flora, symbolically (mutually beneficent) 

 associated with the root system, mutually essential to active development. 

 The importance of soil bacteria in setting free plant foods has been dem- 

 onstrated by numerous investigators of Europe and of the United States. 

 Yeast and mould organisms are practically utilized in the manufacture of 

 beer, sake, and other food and drink products. 



The above condensed outline of the history of bacteriology may be 



summed up as follows: 

 2 



