. A text-book upon the pathogenic Bacteria and Protozoa for students of medicine and physicians. Bacteriology; Pathogenic bacteria; Protozoa. 40 Structure and Classification of Micro-organisms Aciinomyces—The chief characterization of the organisms of this group is a clavate expansion of the terminal ends of radiating fila- ments. These are seen in sections of diseased tissues containing the organisms, but rarely are well shown in the artificial cultures. For further particulars of these organisms see Actinomyces bovis, etc. THE YEASTS, OR BLASTOMYCETES The organisms of this group are sharply
. A text-book upon the pathogenic Bacteria and Protozoa for students of medicine and physicians. Bacteriology; Pathogenic bacteria; Protozoa. 40 Structure and Classification of Micro-organisms Aciinomyces—The chief characterization of the organisms of this group is a clavate expansion of the terminal ends of radiating fila- ments. These are seen in sections of diseased tissues containing the organisms, but rarely are well shown in the artificial cultures. For further particulars of these organisms see Actinomyces bovis, etc. THE YEASTS, OR BLASTOMYCETES The organisms of this group are sharply separated from the bacteria by their larger size, elliptic form, and by multiplication by gemmation or budding. Each organism is surrounded by a sharply defined, doubly contoured, highly refracting, transparent cellulose envelope. Com-. Fig. g.'—Blastomycetes 'dermatitidis. Budding forms and mycelial growth from glucose agar (Irons and Graham, in "Journal of Infectious Diseases"). monly each cell contains one or more distinct vacuoles. When multiplication is in progress, smaller and larger buds are formed. The yeasts, of which Saccharomyces cerevisias may be taken as the type, are active fermentative organisms, quickly splitting the sugars into CO2 and alcohol, and are largely cultivated and used in the manufacture of fermented liquors and bread. They grow well in fermentable culture-media and most of them also grow upon the ordinary laboratory culture-media. Many varieties, some of which produce red or black pigment, some no pigment at all, are known. They play very little part in the pathogenic processes. Burse has observed a case of generalized fatal infection caused by an yeast that he calls Saccharomyces hominis. Gilchrist, Curtis, Ophlils, and others have seen localized human infections by blasto- mycetes. (See Blastomycetic dermatitis.) Ashford* has described a pathogenic yeast to which Andersonf has * "Journal of Tropical Diseases and Preventive Medic
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