AGRICULTUEAL BACTERIOLOGY. 



CHAPTER I. 

 DEVELOPMENT OF BACTERIOLOGY. 



NOWHERE in the whole realm of human endeavor has research 

 been crowned with more glorious achievements, at least in so far 

 as the welfare of the human race is concerned, than in the field of 

 bacteriology, and this in face of the fact that bacteriological research 

 had a most humble and recent origin. Even the dawn of bacteri- 

 ology dates back only to the last quarter of the seventeenth century 

 to the time when a Dutch linen-draper, Anton van Leeuwenhoek, 

 spent his leisure time in grinding lenses. He became so proficient 

 in this that his lenses were superior to any made before. Turning 

 them on various substances raindrops, saliva, and many putrifying 

 things he found in all these living, moving forms, which prior to 

 this time had been unrecognized. We can imagine his joy and 

 surprise from this statement: "I saw with wonder that my 

 material contained many tiny animals which moved about in a 

 most amusing fashion. The largest of these A (Fig. 1) showed 

 the liveliest and most active motion, moving through the water 

 or saliva as a fish of prey darts through the sea; they were found 

 everywhere, although not in large numbers. A second kind was 

 similar to that marked B (Fig. 1) which sometimes spun around 

 in a circle like a top. These were present in larger numbers and 

 sometimes described a path like that shown in C to D (Fig. 1). A 

 third kind could not be distinguished so clearly; now they appeared 

 oblong, now quite round. They were so very small that they did not 

 seem larger than the bodies marked E, and besides they moved so 

 rapidly that they were continually running into one another. They 

 looked like a swarm of gnats or flies dancing about together. I had 

 the impression that I was looking at several thousand in a given 

 part of the water or saliva mixed with a particle from the teeth no 

 larger than a grain of sand, even when only one part of the material 

 was added to nine parts of water or saliva. Further, the greater 

 part of the material consisted of an extraordinary number of rods, 

 of widely different lengths, but of the same diameter; some were 

 2 



