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TTTO FIGURES Cowdry ('18) investigated the cytology of 10 slime molds, primarily on the basis of stained slides prepared by the paraffin method. This work provided the first clear demonstration that mitochondria are present in myxomycetes ; some attention was also devoted to the vacuoles, nuclei, and general protoplasmic structure. Howard ( '31, '32) added cytological information concerning Physaruum polycephalum, especially with reference to nuclear structure in both resting and dividing stages. Andresen and Pollock ('52) presented detailed data concerning the percentage volume of nuclei, vacuoles, mitochondria and pigment granules in the plasmodium of this same species. They also attempted to separate the cytoplasmic inclusions by centrifugation in. vim, but found it difficult to obtain reproducible stratification of particulates within the intact organism. Sponsler and Bath ('53) obtained electron micrographs from plasmodia1 material of P. polycephalum which show some particles 6000 A" in diameter, some 1500 A", some 300 A", and some of other sizes, suggesting that a wide variety of submicroscopic particle types may eventually be disclosed.
Despite the reputation slime molds have long held as classical examples of "protoplasm" the functional aspects of their protoplasmic particulates have been poor 1 y investigated.