EXPERIMENT STATION BULLETINS 225 



scarcity of organic matter and in many cases of moisture. Moisture and 

 organic matter in the soil govern the activity and change connected with 



it, and indicate the value of the land. 

 Animals To make this heading coordinate with air, water, and soil, 



and would be an illogical division, and to make it subordinate is not 



Plants. reasonable. It is distinct. Animals and plants shelter bacteria 



and influence their distribution so greatly that it may truth- 

 fully be said that they would have no distribution were it not for these 

 agents. Diseases of animals, tuberculosis, for instance, would not extend 

 from pole to pole, if it were not through the instrumentality of animals. 

 Diseases of plants do not differ much in this respect. Established facts 

 bear out this statement and point out the relation of bacteria to animals 

 so far as distribution is concerned. Aside from animals and plants there 

 are doubtless other means operating about which nothing is known. With 

 the amount of work that is now under way, it is fair to predict that the 

 avenues of travel used by bacteria will gradually become familiar to bac- 

 teriologists in the near future. Methods will be devised to intercept them 

 in their movements. 



BACTERIAL FUNCTIONS. 



Meat placed away for a short time will often reveal red and yellow spots 

 and in fact spots of almost any color. 



Many have witnessed a pool of water which would change in color as a 

 changeable silk, when viewing it from different places. 



The phosphoresence of the sea has been marveled at repeatedly. All 

 have heard about it if not seen it. 



Every housewife is conversant with the methods of using yeast to make 

 bread, and wonders how a bit of yeast will render light a panful of bread 

 dough. 



The dairyman waits for the souring of his milk with the same degree 

 of assurance as he awaits the arising of the sun. 



The farmer makes his cider and regrets that it becomes vinegar so quickly. 



There are very few who have not looked over the surface of a swamp and 

 seen air bubbles rising to the surface of the water. 



Meat will decompose before it is consumed and in this condition it has 

 been eaten to the detriment of health. 



Villages have been poisoned by attending an ice cream festival or drink- 

 ing the milk procured from a single milkman. 



All these phenomena have come to the attention of everybody. Have 

 they all a meaning and are they associated with bacteria? Some of them 

 suggest a lengthy treatment, yet at this stage satisfaction will have to be 

 gained from very brief statements, since in some of these matters future 

 consideration will be given. When bacteria are studied in their above 

 relations one simply studies their offices in nature, what they do and to 

 what products they give rise. This part of bacteriology is one of the most 

 useful, fruitful, and practical relations of bacteria. Perhaps the investiga- 

 tion of bacterial products has led to more beneficial results than any other 

 line of the science. The suggestions made at the beginning of this subject" 



upon functions only introduce us to a wide field of research. 



(jhromo- For many years there has always been food for superstitious 



genie people in the fact that spots of blood would appear upon their 



Bacteria. meat or bread. They considered them to be drops of blood 



deposited there by some supernatural power. At other times 



29 



