8 PHARMACEUTICAL BACTERIOLOGY. 



affect trees and other plants, fishes and other animals, as well as man. Dr. 

 Mead declared that epidemics were caused by (i) diseased persons, (2) 

 goods imported from infected places, and (3) a vitiated or poisoned state of 

 the air, notions which may be considered as the direct forerunners of the 

 germ theory of disease. 



Let us now go back and consider the ancient ideas regarding spontane- 

 ous generation. Anaximander, of Miletus, who lived during the forty- 

 third Olympiad (610 B. C), believed that many animals developed de novo, 

 from moisture and water acted upon by sun and warmth. The extremist, 

 Empedocles of Agrigentum (450 B.C.), declared that all living things upon 

 the earth were capable of originating spontaneously. Aristotle (384 B. C.) 

 taught that some plants and animals originated spontaneously. Ovid, some 





b 



Fig. I. — From the Arcana Nalurm of A. van Leeuwenhoek. The first published 

 illustration of bacteria. These bacilU of the mouth cavity were seen with the aid of simple 

 lenses only, a, b, bacilli ; c, a spirillum ; e, perhaps chain forms of bacilli ; d, illustrating 

 the characteristic motion of certain bacilli (n to m). 



three centuries later, gives instructions how to create bees spontaneously in 

 the carcasses of horses. To within recent times the belief that certain 

 animals could originate spontaneously, that is, without a pre-existing parent, 

 was quite general, and differed only in grotesqueness. Cardan as late as 

 1542 declared that water created fishes, and that many fermentative proc- 

 esses created animals. Van Helmont gives instructions how to produce mice 

 artificially. Kircher boldly declared that he had seen certain animals 

 develop spontaneously before his eyes. Paracelsus gives instructions how to 

 make homunculi. The instructions are quite simple. Certain substances 

 are placed in a bottle, the bottle is well stoppered and buried in a manure 

 heap. Every day certain incantations must be pronounced over the bottle 

 in the manure heap. In time, Paracelsus declared, a small living human 

 being (homunculus) will appear in the bottle. Paracelsus, however, naively 



