STUDY OF FORMS 31 



and natural history of bacteria. He described spore forma- 

 tion and the development of spores into active bacteria, 

 and showed the close relationships as well as differences 

 between the bacteria and the lower algse. Robert Koch 

 was a pupil of Cohn. 



An examination of the accompanying chronological table 

 will show how the investigations and discoveries in con- 

 nection with "spontaneous generation," the "contagium 

 vivum" theory and putrefaction and fermentation must 

 have been mutually suggestive: 



1546. Fracastorius, disease germs theory and direct and 

 indirect contagion. 



1671. Kircher, " contagium vivum" theory. 

 —1675. Leeuwenhoek, first saw bacteria, "animalcules." 



1701. Andry, "animalcules" cause of diseases. 



1718. Lancisi, " animalcules" cause of malaria. 



1749. Needham, described development of organisms in 

 water around barley grains. 



1762. Plenciz, arguments for "living cause" theory and 

 that "animalcules" cause putrefaction. 



1768. Bonnet, suggested that probably Needham's organ- 

 isms came from germs in the liquid. 

 ~ 1776. Spallanzani, boiled and sealed infusions. 



1786. Miiller, first classified "animalcules." 



1787. Wollstein, glanders pus infectious. 

 1797. Viborg, transmitted glanders repeatedly. 



- — 1807. Prevost, grain rust, Puccinia graminis. 

 1810. Appert, directions for "canning." 

 1822. Gaspard, infectiousness of material from wounds. 

 1834. Renucci, itch — itch mite {Sar copies scabiei). 



1836. Schultze, air through acid to kill "germs." 



1837. Chevreuil and Pasteiu-, protected meat did not 



putrefy; suggested wound infection due to entrance 



of germs from without. 

 1837. Caignard-Latour, Schwann, alcoholic fermentation 



— yeast. 

 1837. Schwann, air through heated tubes to kill germs. 

 1837. Bassi, muscardine of silkworms, Botrytis hassiana. 



