SQ ILLINOIS STATE DAIRYMEN's ASSOCIATION. 



proper investigation, cannot avoid them if he enters upon the sub- 

 ject at all. The microscope shows in the solution from rennet as 

 much of the germ theory of change as it does in the fermentation of 

 milk when left exposed in the ordinary manner, and this evidence is 

 convincing in a very high degree. Other phenomena coincide to 

 make the conclusion irresistable. The living organism in the rennet 

 is killed by heat, it propagates itself in a suitable liquid with the 

 astonishing rapidity of its congeners usually found outside of living 

 animals ; a little used as seed permeates a great bulk of nutritive 

 substance, as a little leaven (yeast, a plant) in the olden as well as 

 the modern time, leavened the whole lump. The rennet plant can 

 thus be cultivated, as the yeast plant is, and possibly in a much more 

 convenient method than at present known. It is a plant, living, 

 multiplying, absorbing, assimilating, dying — very low in the scale of 

 classification, and scarcely diflPering from the equally low forms of 

 animal life, yet having a definiteness and individuality which in 

 some respects those of the highest rank, the lords of creation, might 

 do well to imitate. 



Let this example suffice. If the coagulation of sweet milk, by 

 the aid of rennet, can be proved to be due to the action of organisms 

 in a living state are we not prepared to accept the same or a similar 

 agency for any change which we observe in this, apparently, un- 

 stable fluid ? But the evidence concerning some of these changes, as 

 that of souring, is still more direct, certainly better and more gener- 

 ally known. We cannot be far wrong in concluding that all the pro- 

 cesses, through which milk and its products pass, are results, direct 

 or indirect, of living, lowly organized plants or animals. Customers 

 say the higher organized animals have something to do with certain 

 changes of which we do not speak. 



What is the nature of the microscopic creatures to which such 

 marked results are attributed ? The word fungi, now in general use, 

 is commonly introduced whenever any name is applied to the organ- 

 isms with which we have to deal. But this is applied to an immense 

 order of plants of which the members diff'er among themselves 

 almost as much as the trees of the forests and grasses of the fields. 

 They have something in common as to their food and mode of life; 

 but differ wondrously in appearance, in size, in method of propaga- 

 tion, etc. There are probably not less than twenty-five hundred 

 species of fungi growing naturally in Illinois. Some are found upon 

 old logs, some on upright trunks, some on or in the soil, some only 



