. Biology. Biology. 60 ORGANISMS OF ONE CELL TfflCHOCYSTS GASTfVC VACUOL£. C. A CILIATED PROTOZOON, PARAMECIUM CAUDATUM An infusion of vegetable or animal matter becomes the feed- ing ground not only of bacteria and flagellated protozoa, but also, after some considerable time, of ciliated protozoa as well. Prom the fact that all of these organisms appear in such infu- sions, the term Infusoria was formerly employed to designate all of them indis- criminately. The bacteria were first recognized as having no systematic rela- tion to the other forms, and were separated in classification from the

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. Biology. Biology. 60 ORGANISMS OF ONE CELL TfflCHOCYSTS GASTfVC VACUOL£. C. A CILIATED PROTOZOON, PARAMECIUM CAUDATUM An infusion of vegetable or animal matter becomes the feed- ing ground not only of bacteria and flagellated protozoa, but also, after some considerable time, of ciliated protozoa as well. Prom the fact that all of these organisms appear in such infu- sions, the term Infusoria was formerly employed to designate all of them indis- criminately. The bacteria were first recognized as having no systematic rela- tion to the other forms, and were separated in classification from the pro- tozoa found in infusions. Later the flagellated forms were recognized as entirely different from the ciliated ones and were classified under the name Mastigo- phora, so that finally, the term Infusoria is used today to include only the ciliated forms of protozoa. Of these there is a great number of different types, one of which, Paramecium, formerly known as the "slipper animalcule" com- mon in every ditch, pool, or stagnant water, may r -n serve as a type for all. Paramecium is an elon- gated, somewhat cigar-shaped organism, consisting of a single cell which moves rapidly through the water, turning the while on its long axis. The movement is brought about by the A^Sjf-> H "•:': v. &. 4 '3=5. pSRISTOME MOUTH AflO> GULLET CONTRACTILE VACUOLE. FIG. 26. — Diagram of structures of Para- mecium caudatum from an individual about yl25 of an inch in length.. 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 work.. Calkins, Gary N. (Gary Nathan), b. 1869. New York, H. Holt and company