CHAPTER I 

 INTRODUCTION: MORPHOLOGY 



Form, Size, and Structure of the Bacterial Cell, Cell-membrane, 



and Cell-contents. 



THE first historically recorded discovery of bacteria was made more 

 than two hundred years ago by Anton van Leeuwenhoek, the Dutch 

 naturalist and pioneer in the world of the infinitely little. Exploring those 

 then untravelled regions with home-made lenses of wonderful efficacy, he 

 found in the saliva of the human mouth 

 minute organisms to which he gave the a 



name of animalcula on account of their ^ JV< = ::: => ...... 



power of movement. ... .......... ! 



In the description (1) and in the figures JL B &,""'"' 

 he gives (reproduced in facsimile in Fig. i), 

 curved and straight forms and long and 

 short rods are plainly recognizable. They c/ff : 

 constitute the earliest reliable record of 

 bacteria, the study of which in later times 



has revolutionized medicine and expanded 

 into a new science. From the year 1683 

 Leeuwenhoek's observations stood alone 



, i T>V i FlG. I. Oldest known figures of genuine 



Until, a Century later, the Danish Savant bacteria (bacteria of the mouth) from Leeu- 

 _ .. , wenhoek. A and f represent Bacillus buc- 



Muller made further investigations on bac- / maximus. B is perhaps vibrio 



.,.- . buccalis\ its movements were followed by 



tei'ia. He Classified them With the lllfuSOria Leeuwenhoek from C to D. E is a species of 



coccus, and G, no doubt, a Spirillum sputi- 



and gave them names that are now familiar genum (compare with FIG. 26). 



to us all, Vibrio, Spirillum^ and Bacillus. 



In 1838 Ehrenberg described in his great work on infusoria a large number 



of bacterial forms, ranking them with his group Vibrionia, and from this 



time forward the bacteria have never again drifted entirely out of sight. 



It was not, however, until about the seventh decade of this century that 



