HISTORICAL. 9 



admits that he has never succeeded in inducing the homunculus to continue 

 alive after being taken from the bottle. Gradually these grotesque and 

 extreme opinions regarding spontaneous generation were abandoned, and it 

 was declared that only the lower plants and animals, such as seaweeds, algae, 

 lichens, lice, mites, maggots, etc., could develop spontaneously. -In fact, 

 we can find fairly intelligent individuals to-day who firmly believe that 

 certain animals, as lice, mites, etc., can originate without a parent, and that 

 the hair from the tail or mane of a horse will change into a worm or snake if 

 placed in a bottle of water and exposed to light and warmth. 



From the earliest records we learn that the value of disinfectants in pre- 

 venting the spread of infectious diseases (epidemics and plagues) was known. 

 Ovid states that the shepherds of his time used burning sulphur for bleach- 

 ing wool and to free it from infectious diseases. In times of plagues, big 

 fires were made to stay the ravages of pestilential diseases. The Mosaic 

 law is replete with instructions regarding cleanliness as a means of pre- 

 venting disease. Wine was highly valued as a dressing for wounds, having 

 the effect of preventing or checking pus formation. ) 



Period II. 



From Leeuwenhoek (1656) to Schwann (1837). (Discovery of 

 micro-organisms and the early investigations regarding their 

 activities.) 



As early as 1646 Kircher suggested that certain diseases might be due 

 tojery_jnjnutfi organisms which were supposed to originate spontaneously 



FIG. 2. From Arcana Naturae. Cell structure of cork. Cell-lumen is shaded and cell-walls 



are shown light. 



under certain conditions. Anton van Leeuwenhoek is very justly called the 

 father of microscopy, and to him must undeniably be given the credit of 

 first having discovered and actually figured microbes and other micro- 

 organisms. His Arcana Nature was published in 1656 in four volumes. 

 It is a most interesting work, and contains many good illustrations showing 



