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Publisher Summary This chapter discusses the macronuclear variability of Blepharisma associated with growth. Ten different strains of the genus Blepharisma were selected for comparative studies of their nuclear and cytoplasmic growth from the twenty different strains in culture in the laboratory. A cyst-producing strain from Hingham, Massachusetts, was included among the ten strains. The different species, when grown at 18°C and fed upon bacteria, are morphologically distinguishable as species. The two strains of B. undulans, while they are distinctively different physiologically, are not sufficiently morphologically different to separate them at present into different species. Studies of the effects of different types of nutrition, combined with exposures to 5°C and 36°C, showed that at the high and low temperatures, although there were at first differences in reaction, ultimately all of the species were so drastically altered that they became morphologically indistinguishable. Organisms that were exposed to the 5°C again exhibited their characteristic morphology when returned to 18°C. Adaptation to 36°C of some of the organisms of one species fed on Tetrahymena occurred. That species was B. seshachari. The adapted individuals maintained their species characteristics. |
