214 



STATE BOARD OF AGRICULTURE 



THE SCIENCE OF BACTERIOLOGY. 



Bacteriology has for its aim the study of bacteria, in their morpholof2;ical 

 a id chemical aspects. Often the yeasts occupy a share of the science along 

 with certain moulds, pfobably for no other reasons than their close rela- 

 tions to bacteria and the similarity of the methods used for the study of 

 each. Yeast fermentations have always been associated with the study of 

 bacteria. Pasteur united them under one common and natural department 

 of experimentation by his early labors upon fermentation, 



WHAT ARE BACTERIA? 



It is not safe to attempt a definition inasmuch as many modifications 

 would be necessary. A few of their characteristics may be mentioned, and 

 these will convey to the reader sufficent data to formulate in his own mind 

 a satisfactory notion of these minute forms of life. They are 

 unicellular plants; that is, instead of possessing a complex struc- 

 ture of many cells, as the plants visible to the naked eye, they 

 are but single cells, translucent, and have a definite form. In 

 their multiplication, one cell divides and produces two, each 

 of these two divides and both together produce four. A yeast 

 cell, instead of multiplying by division or fission, increases by 



Definition 

 Bacteria. 



Yeast. 



Mooldfi. 



Fig. 1. Yeast cells. 



budding. From the parent cell buds off a daughter cell, 

 smaller than the parent cell. In moulds the growtij is much 

 like twigs, with the formation of long thread-like shoots. 



CLASSIFICATION OF BACTERIA. 



In the animal and plant kingdoms classifications are based largely upon 

 anatomical structures and physiological functions. Form does not take a 

 part to any great extent. Owing to ignorance of the structure and func- 

 tions of the bacterial cell, a classification based upon them is infeasible; 



consequently the classification rests entirely upon the form 

 Bacillus- which is easily studied. Three distinct forms exist. Tht^ first 

 Shape. is a rod shaped cell, called a bacillus — plural, bacilli. Conceive 



little translucent rods, with rounded, tapering or square t^uds, 



