PART I 



THE MORPHOLOGY AND CULTURE OF MICRO- 



ORGANISMS 



GENERAL* 



Microbiology is concerned with organisms which range between 

 well defined plant life on the one hand, and well defined animal life 

 on the other. These living forms are in the main unicellular in 

 structure. A gradation exists from the plant world into this mi- 

 crobe-world and also from the animal world. No sharp lines can 

 be established because Nature seems to blend from one type into 

 another leaving no particularly characteristic barrier, although man, 

 for his own convenience, strives to construct Nature with very 

 definite lines of demarcation. Haeckel was so impressed with the 

 organisms which lie between the animal and plant world that he 

 found it undesirable to attempt to classify them in the one or the 

 other kingdom. Accordingly, he believed it of sufficient importance 

 to give a specific name, Protista, to the microorganisms included in 

 this specific kingdom. This relationship is clearly set forth by an 

 illustration furnished by Minchinf (Fig. 2). 



Morphology has been paramount in classification in the past, yet, 

 at first, bacteria were called animals and later plants. With the ad- 

 vancement and importance of physiology, it becomes necessary to 



* Editor. 



t Minchin, E. A.: An Introduction to the Study of the Protozoa. 



II 



