. Protozoo?logy. Protozoa; Protozoa, Pathogenic. MORE COMPLICATED LIFE CYCLES 123 cell, they certainly are not connected with the formation of the gametic nuclei. On the other hand, there can be no doubt of the propagative nature of such distributed granules in the great majority of protozoa, and in such cases we may, with reason, speak of a definitive germ Fig. 52. Life cycle of Polystomella crispa S. (Lang and Schaudinn). A young form derived from the union of two flagellated gametes (A) de^-elops into an organism with microspheric type of shell. The nucleus increases by mitosis until many n
. Protozoo?logy. Protozoa; Protozoa, Pathogenic. MORE COMPLICATED LIFE CYCLES 123 cell, they certainly are not connected with the formation of the gametic nuclei. On the other hand, there can be no doubt of the propagative nature of such distributed granules in the great majority of protozoa, and in such cases we may, with reason, speak of a definitive germ Fig. 52. Life cycle of Polystomella crispa S. (Lang and Schaudinn). A young form derived from the union of two flagellated gametes (A) de^-elops into an organism with microspheric type of shell. The nucleus increases by mitosis until many nuclei are present when they break up into granules of chromatin (B). The protoplasm fragments into reproductive bodies, equivalent to merozoltes (C), each having several granules of the distributed chromatin ("Chromidien"). Each reproductive body (D) develops into an adult with a macrospheric type of shell, and with nuclei in the form of small chromatin granules (E). When mature these forms fragment into hundreds of flagellate gametes (F) which conjugate, and so com- plete the cycle. (See, also, Fig. 41, p. 114.) plasm as contrasted with the somatic plasm. With such an assump- tion we are brought in touch with a problem of high theoretical interest in general cytology, and with the protozoa, as with the metazoa, we have this question to consider: Are there two kinds of substances in. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Calkins, Gary N. (Gary Nathan), b. 1869. New York and Philadelphia, Lea & Febiger
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