202 AGRICULTURAL EXPERIMENT STATION. [Jan. 



acid, which occurs when cider is converted into vinegar ; 

 another produces the rancidity of Ijutter ; and so on, through 

 a long list. Many of the parasitic bacteria live in the bodies 

 of men or other animals, and produce the most dreaded and 

 dreadful contagious or zymotic diseases, like small-pox, 

 anthrax or splenic fever, diphtheria, Asiatic cholera, hog 

 cholera. Southern cattle fever, chicken cholera,, pleuro- 

 pneumonia, and many others. A few, also, produce diseases 

 of plants, especially the rotting of bulbs and tubers. It is 

 also claimed by careful investigators that the, " fire blight" 

 of pear and apple trees is due to the attacks of one of the 

 bacteria. 



These plants reproduce themselves chiefly hy Jission, a 

 process which consists in the elongation of the organism up 

 to a certain point, and the formation of a cross-wall dividing 

 it into halves, which then separate and become independent. 

 In its essentials the process is evidently a simple cutting in 

 two. 



The bacteria are universally disseminated, since their 

 extreme smallness and consequent lightness render them 

 easily transportable by the lightest breezes. When it is 

 remembered that all putrefactive changes are due to their 

 activity, their omnipresence begins to be realized. 



The true Fungi show greater complexity of structure 

 than either of the groups just described. With a very few 

 exceptions, they have a distinct ])lant body or vegetative 

 portion, on which are developed the reproductive organs, or 

 fruiting portion. The plant body consists of fine colorless 

 threads, often branched, which spread over or through the 

 substance from which the fungus draws its nourishment. 

 These active, absorbing, vegetative threads of the plant l)ody 

 constitute the myceliuji of the fungus. From these are 

 ultimately produced others, which are the fruiting or repro- 

 ductive threads of the plant, and bear the reproductive 

 bodies whose function is similar to that of the seeds of the 

 higher plants, namely, the perpetuation of the species. 

 Though produced in widely diflerent ways, and varying 

 among themselves far more than do the seeds of flowering 

 plants, they may be, for convenience, all included under 

 the general name spores. They are much simpler in 



