172 AGRICULTURE OP MAINE). 



the past two years I have been handhng the milk samples of the 

 Inspector of the State Department of Agriculture, and, during 

 this time, I have had occasion to report to him upon a large 

 number of samples, which I have classed as "dirty" in varying 

 •degrees. It has apparently been thought that I must know 

 something of the bacterial contamination which this dirt brings 

 into the milk. What I do know about this subject I will try to 

 present to you. 



In this paper I cannot touch on the part played by all of the 

 varied species of bacteria that occur in milk, nor dwell on the 

 important part that bacteria play in dairying operations, where 

 they are essential to the success of such operations. The sub- 

 ject limits me to the discussion of the bacteria that gain access 

 to the milk through the dirt that falls into it, and so to the harm- 

 ful species rather than to the beneficial ones. In a science as 

 young as is this one of bacteriology there is necessarily great 

 confusion in terms and nomenclature, and the many details of 

 the work are of such interest that there is a constant temptation 

 to u-se language that is almost unintelligible, and to bring in de- 

 tails that are of no interest to a body such as this. As a result 

 I shall, in my attempt to avoid all big words and technical 

 phrases, confine myself very closely to my notes, much as I dis- 

 like to do so. 



First of all a few words in general in regard to bacteria are 

 in order. These things, popularly called "germs," are extremely 

 m.inute vegetable organisms; so minute that, in order to study 

 them, they have to be magnified from 600 to 1000 times their 

 true size. Their variety is infinite, but no more so than is their 

 field of operation. Much of the life work of the world is done 

 by these invisible multitudes. They change useless compounds 

 in the soil into forms that can be used as plant food; they re- 

 turn the elements of both dead animal and vegetable bodies to 

 the earth, and prepare them for renewed use as food for plant 

 and animals ; they are the scavengers who remove dead and de- 

 caying organic matter from our view ; they ripen our cream for 

 butter making ; they change the proteid of cheese into digestible 

 forms ; they produce the pleasant and distinctive flavors and 

 aromas of our hard cheeses ; and on the other hand they make 

 our milk to sour, and they produce disease in the animal body, 

 for they are the cause of diphtheria, typhoid fever, cholera, 



