. Pharmaceutical bacteriology. Bacteriology; Disinfection and disinfectants. YEASTS AND MOLDS 313 spores, appear to be homogeneous with the exception of a comparatively small number of large spherical 0.5 micron granules. The plasmic gran- ules are especially prominent and numerous in the arthrospores and in the arthrospore sphaerocytes. They are highly refractive and stain readily. They are actively motile, especially in the sphserocytes' where they also show remarkable Brownian vibration.. Pig. 83.—^Arthrospore formation and ascospore development of Nematospora. Ordinary vegetative (somatic)

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. Pharmaceutical bacteriology. Bacteriology; Disinfection and disinfectants. YEASTS AND MOLDS 313 spores, appear to be homogeneous with the exception of a comparatively small number of large spherical 0.5 micron granules. The plasmic gran- ules are especially prominent and numerous in the arthrospores and in the arthrospore sphaerocytes. They are highly refractive and stain readily. They are actively motile, especially in the sphserocytes' where they also show remarkable Brownian vibration.. Pig. 83.—^Arthrospore formation and ascospore development of Nematospora. Ordinary vegetative (somatic) cells are gradually transformed into spores; A, arthro- spores derived from vegetative cells; B, an ascospore entering upon a new vegetative cycle; C, detailed structure of a mature ascospore more highly magnified; a, vacuolesin the chromatin-bearing cell of the spore; b, chromatin substance; c, transverse septum; d, plasmic masses in the achromatin cell of the spore; e, achromatin;/, the portion of the ligule which stains very heavily; g, the greatly elongated ligule by means of which the spore attaches itself to various substances with which it is brought in contact. The ascospore is distinctly two-celled. The spore wall as well as the septum^are thin. There is a distinct widening of the spore at'and near the^transverse septum. Ascospore formation is generally the result of the gametic union (isogamous) of two elliptical vegetative cells. The apical cell membranes which are in contact dissolve. The plasmic contents of the two cells fuse. The complete changes are shown in Fig. 81. Eight spores are formed in each spore sac. At an early period in the development of the spore sac (ascus) the associated vegetative cells become separated and the spore sac exists as an independent cell structure. There are indications that a spore sac may be derived from a single vegetative ceU, especially when spore formation becomes very active. As a rule active ascospore formation is accompani