STUDIES OF THE FINE STRUCTURE OF MICROORGANISMS

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Abstract
The budding process of Saccharomyces cerevisiae was followed by means of electron microscopy of thin sections and conventional light microscopical techniques. Lindegren''s modification of the Carnoy-perchloric acid-Giemsa technique was also employed for observing the behavior and structure of the yeast nucleus during bud formation. The electron micrographs revealed that the actively dividing nucleus was highly lobulate in shape and homogeneous in texture. The nuclear membrane was observed to persist throughout the various stages of nuclear division. Structures identifiable as chromosomes were not observed in any of the electron micrographs. The available evidence indicates that sub-microscopic units of chromatin are dispersed throughout the yeast nucleus. The term "cryptomitosis" is proposed to describe the situation in which genetic evidence indicates the occurrence of mitosis, without an adequate or consistent cytological basis. Structure and behavior of various components of the yeast cell during the budding process were also described.