IO PRACTICAL DAIRY BACTERIOLOGY 



MOLDS 



These are plants of considerably larger size and much higher 

 structure, and they do not logically belong to the consideration 

 of bacteria in milk. Their relations to 

 milk and milk products, however, are in 

 many respects very much like those of 

 bacteria, and in certain phenomena asso- 

 ciated wtih the ripening of cheeses they 

 are of as great importance as bacteria 

 themselves. It is necessary, therefore, for 

 the dairyman to know something about 

 them. They are plants that in all cases 

 are large enough to be seen with the naked 

 eye, although the microscope is required 

 to study them. They consist of a mass of 

 branching threads of very minute size. 

 (Figs. 9, 10 and n.) Sometimes the 

 threads are large enough to be seen with- 

 out a microscope and sometimes not. This 

 mass of threads is almost always color- 

 less, or of a pale white, and grows on the 



FIG. 9 COMMON MOLD, ... e 



surface or in the substance of various 



PENICILL1UM 



Method of forming spores materials upon which the plant feeds. On 

 cheeses, for instance, it thrives in pro- 

 fusion upon the surface, and sometimes extends into the cheese 

 itself. There are a great many species of molds, but they 

 are all very much alike so far as concerns the formation of 

 this colorless thread (mycelium'), although there are some 

 differences to be seen here. But molds have methods of mul- 

 tiplication which commonly enable us to distinguish different 

 species. After they have grown luxuriantly, they usually send 

 minute branches into the air, the ends of which finally produce 

 rounded spores, or reproductive bodies. These are sometimes 

 produced in chains, sometimes in masses, and the method of 



