38 MANUAL OF EQUINE MEDICINE. 



of the muscardine disease of silkworms ; and in 1840 Henle 

 expressed a belief that living organisms, probably vegetable 

 in nature, were the causes of the acute specific fevers. 



Long before Schwann and Cagniard de Latour had dis- 

 covered that yeast consisted of cells, probably vegetable in 

 nature, which multiplied by gemmation, a close parallel 

 was noticed between the infective diseases and the pro- 

 cesses of fermentation. 



The germ theory started by Astier, Schwann, and 

 Cagniard de Latour, and perfected by Pasteur is accepted 

 by most scientists of the present day, and all the processes 

 generally known as fermentation and putrefaction are looked 

 upon as due to the action of vegetable organisms. 



Now various micro-organisms have been demonstrated in 

 the blood and tissues of animals suffering from various in- 

 fective disorders, of which group the acute specific fevers 

 form a division. 



These organisms are of a vegetable nature, and as they 

 possess neither root, stem, nor leaves, are referred to the 

 Thallophyta. They have no chlorophyll, or green colour- 

 ing matter, and they thus form a group of the class of 

 Fungi. 



There are three kinds of pathological fungi : 



(1) The Bacteria, or Schizomycetes, e.g.^ Bacillus An- 

 thracis. 



(2) The Yeasts, or Blastomycetes, e.g., Oidium Albicans. 



(3) The Moulds, or Hyphoniycetes, e.g., Tinea Tonsurans. 

 The Bacteria, besides causing putrefaction and several of 



the fermentations, include almost all the organisms which 

 are believed to cause the infective diseases. 



THE BACTERIA OE SCHIZOMYCETES are unicellular, 

 strongly refractile, very minute organisms. They vary in 

 shape, and appear to be structureless, though they may 

 possess a cell-membrane allied to cellulose. They may be 



