260 



SCIENCE 



[N. S Vol. XLII. No. 1078 



which have a role to play and others doubt- 

 less whose work and values we in our ignor- 

 ance do not recognize. 



Soil in the light of microorganisms may 

 be regarded as a substance having for its 

 basis or groundwork mineral constituents 

 of geological origin to which has been added 

 organic matter. Through the fermenta- 

 tions and changes in the organic matter 

 and the solution of mineral substances in- 

 cited by microorganisms such products are 

 formed which give to plants their exist- 

 ence. The mineral constituents forming 

 the basis must be those, of course, essential 

 to the construction of vegetable tissues, and 

 the organic matter after decomposition such 

 as will contribute required food. The con- 

 tinuity of the supply is paramount. After 

 all the elements are present and the condi- 

 tions for microbial and plant life pro- 

 vided, the active or operating machinery of 

 the soil is resident in its microorganisms. 



It follows also from the above — a matter 

 of great importance to the microbiologist — 

 that soil types are as variable as their geo- 

 logical formations, the mineral constituents 

 which give them their character, and the 

 organic substances which enter into their 

 fertility. This variability is heightened 

 when to it is added a consideration of the 

 varying amounts of mineral and organic 

 substances present. Soil, therefore, as we 

 have employed the term, can not be inter- 

 preted from any one type or several types, 

 but rather specific instances and specific 

 types formed under known conditions. 

 Soil, defined by its structural parts, unless 

 concretely and definitely applied to some 

 type, has no existence, but when so defined 

 holds its physical, chemical and biological 

 factors, harmoniously united in its mineral 

 and organic composition. 



The daily as well as soil offers interest 

 to the agricultural microbiologist. 



In a sense it is a veritable microbiological 



laboratory instituted for commercial pur- 

 poses. On the other hand, to the dairjrman 

 it is a great industry based upon several 

 elemental sciences and other distinctive in- 

 dustries. Furthermore, it is concerned 

 with the preparation of milk and milk 

 products for the consumer. Microbiology 

 is only one support in this extensive food 

 manufacture. Our approach is micro- 

 biological and our treatment will be its 

 interpretation from this viewpoint, which 

 has been greatly emphasized during the 

 past twenty-five years. 



Cow's milk can not receive full approval 

 without the vital and broad question of 

 disease transmission from the animal at 

 once arising. Although knowledge of the 

 importance or extent was at first extremely 

 meager and indefinite, growth has occurred 

 from the time when Klein wrestled with the 

 probabilities of communicating diphtheria 

 through the blood and milk till the present 

 moment which grants specific information 

 and satisfaction in the matter of the most 

 serious diseases. Tuberculosis has assumed 

 huge dimensions within the memory of 

 most of us, for it came into the limelight of 

 popularity by Koch's discovery of tuber- 

 culin, a discovery which alone has paid for 

 all the time and means expended upon 

 microbiology since the days of Schwann. 

 As an illustration of doubt and the stage of 

 dilemma and misty ideas necessary to the 

 decisive solution of all weighty questions, 

 the present furnishes the milk producer and 

 microbiologist with the "dairy septic sore 

 throat." These allusions, however, indi- 

 cate very slightly how great is the "micro- 

 biological purity" of milk as it emerges 

 from the cow. 



Then as the milk is exposed to the con- 

 taminations of the milker, the air, the 

 utensils and the stable, or as it passes 

 through the paths and by-paths of the milk- 

 ing process — the most crucial undertaking 



