CHAPTER XXI. 

 SCHIZOMYCETES l (BACTERIA) SACCHAROMYCES (YEAST). 



PRINCIPAL MATERIALS USED. 



Spontaneous cultures of various Bacteria in infusion of lettuce (or other) 

 leaves, and of peas, and on discs of boiled carrot, turnip and potato. 



Fur of teeth. 



Water 'with decaying Confervse ; or filtered infusion of pea-flour, decom- 

 posing ; for Spirochcete. 



Hay-infusion ; for Bacillus subtilis. 



Decaying peas or beans for Bacterium Termo. 



Brewer's Yeast (barm). 



Many special materials and appliances may be used, for which see text. 



PRINCIPAL REAGENTS USED. 



Indian ink Iodine 3 per cent, potash A stain, such as methyl violet, 

 gentian violet, fuchsin, or methylene blue Ehrlich's aniline-water- 

 fuchsin and methylene blue Many special reagents and stains are 

 used, and will be found described in the text. 



LET us now turn our attention to examples of the group of 

 smallest known organisms, the Bacteria, in order to obtain some 

 general information as to the forms they may assume. The great 

 importance which has in recent times been attached to these 

 organisms, as playing an active part in many important indus- 

 tries, but especially as a means of transmission of infectious 

 diseases, has resulted in an enormous expansion of their study. 

 Bacteriology has become a special branch of botanical and medi- 

 cal science,, and is treated in numerous comprehensive treatises. - 



1 Segmenting, splitting or fission-fungi. As a convenient term for an 

 individual, not implying any special kind, I use the word " bacteriad ". [ED.] 



- An exceptionally valuable example of the scientific method of treating 

 a bacteriological problem is found in H. Marshall Ward, "The Ginger-beer 

 Plant, and the organisms composing it : a contribution to the study of 

 Fermentation-Yeasts and Bacteria " ; Phil. Trans., 1892 B, pp. 125-197, and 

 Plates 11-16. [Ed.] 



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