36 Proceedings of Indiana Academy of Science 



The life of the higher beings is intimately associated with these 

 smaller organisms; in fact the higher forms would be impossible without 

 the lower ones. 



When one recognizes that these micro-organisms are continually 

 at work breaking down dead matter and preparing the way for new 

 life one realizes that they are beneficial and indispensable. 



A great practical industrial significance is attached to these one- 

 celled organisms because many of the products, such as the alcohols, 

 acetone, acetic, butyric and lactic acid and other organic compounds 

 to which they give rise are directly utilized by man. In our own State 

 of Indiana we have a mammoth plant which employs the industrious 

 bacteria in the production of organic solvents used in commerce. 



The vast deposits of sodium nitrate (soda saltpetre) in South 

 America and the potassium nitrate (saltpetre) of India owe their 

 origin to the action of bacteria on the guano, an excrement of birds. 



Bacterial activity occurs to a large extent in the production of 

 foods. Special flavors and characteristics in foods such as butter, cheese, 

 sauerkraut, pickles, ensilage and koumiss are largely due to the de- 

 sirable fermentative changes which occur. 



The dairy industry has been revolutionized within the last few 

 years due to the recognition of the role bacteria play in the manufac- 

 ture of such products. With the knowledge that dairy products may 

 give rise to certain diseases, the cows, as well as those employed in 

 and about milk producing and handling establishments, are examined 

 for certain bacterial diseases of which tuberculosis and latent typhoid 

 fever are outstanding. 



It is well known that bacteria develop non-poisonous chemical prod- 

 ucts, especially resembling certain of the poisonous vegetable alkaloids, 

 when grown upon nitrogenous foods as meats and cheese, as well as 

 in the cadaver. And because of their occurrence therein great impor- 

 tance was attached to them in legal medicine. Until the researches of 

 Selmi revealed this fact undoubtedly convictions of otherwise innocent 

 persons were committed. 



It is now a recognized fact that there is practically no such thing 

 as ptomaine poisoning. The ill eff'ects, to an overwhelmingly large per 

 cent, are due to acute infections primarily with Bacillus enteritidis, 

 the para typhoid organisms and to the highly poisonous soluble products 

 of bacterial growth (botulinus toxin). This knowledge has taught us 

 how to more intelligently handle and prepare foods. 



Micro-organisms also play an important part in the tannery as 

 depilatories, in the bating and the tanning of leather. The flax and 

 hemp industries are dependent upon bacterial activity; and the fer- 

 mentation of such origin has proved of value in the handling of hay 

 and the curing of tobacco. 



Primative man thousands of years ago, although soil bacteriology, 

 of course, was unknown, recognized the value of fertilizers; transfer of 

 rich top soil to new or arid tracts; soil tillage; rotation of crops and 

 green manuring. The members of the bean family were also con- 

 sidered as special soil enrichers. 



