BACTERIA. 



BACTERIA flourish only in the presence of moisture, but 

 are found in soil and air; indeed hardly any condition where 

 life is possible is devoid of bacteria. Some are among the 

 most useful and important of organisms, and others are 

 among the most dreaded and dangerous of all living things. 

 Many of the most virulent of diseases which afflict mankind 

 have been traced directly to bacteria. Some study of their 

 peculiarities, conditions of activity, method of protection 

 from them may be of interest and importance economically 

 and biologically. 



I. Morphology. 



Mount a drop of water from a hay or other infusion of 

 organic matter, or from slime in aquaria, and examine under 

 the highest power of the microscope. Note the numbers of 

 very minute, almost transparent bodies present, some in 

 motion and others quiescent. 



The forms of bacteria are very simple and comprise only 

 three principal types: the sphere- (coccus), the rod (bacillus), 

 and the spiral (spirillum). How many of these kinds are 

 distinguishable in your preparation? Is the size variable? 

 Which type is generally largest, and which smallest? Is 

 the movement which is taking place a locomotion or merely 

 a vibration or oscillation? 



Make drawings to show the shape and relative size of the 

 types of bacteria found. 



