. Protozoo?logy. Protozoa; Protozoa, Pathogenic. 70 PHYSIOLOGICAL ACTIVITIES OF THE PROTOZOA meant by Ehrenberg, the protozoa today offer a field of research in physiology that is Cjuite unique, for while they epitomize the vital activities of the higher animals, these activities are of such simple types that they may be more easily observed and correlated with the ordinary reactions in physics and chemistry, reactions which we do not associate with the vital processes of the higher animals. The warning may not be out of place here that despite the simplicity of function in the protozoon, and

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. Protozoo?logy. Protozoa; Protozoa, Pathogenic. 70 PHYSIOLOGICAL ACTIVITIES OF THE PROTOZOA meant by Ehrenberg, the protozoa today offer a field of research in physiology that is Cjuite unique, for while they epitomize the vital activities of the higher animals, these activities are of such simple types that they may be more easily observed and correlated with the ordinary reactions in physics and chemistry, reactions which we do not associate with the vital processes of the higher animals. The warning may not be out of place here that despite the simplicity of function in the protozoon, and the analogy with reactions in the inorganic world, there is, nevertheless, a power of acting as a whole, a power of coordination combined with factors of adaptation and Fig. 21. Food-taking, A, after Penard; B and C, after Biitschli. A, Raphidioplirys elegans, H. and L.; B, Oikonionas ternao, Elir.; C, Didinum nasutum, O. F. M.; j, food particles. evolution, which permit of development into more and more com- plicated structural units, which arises, per se, in all protoplasm, and raises it immeasurably above the most complex of non-living sub- stances; this power of adaptation is an inherent characteristic of living matter, transcending physical or chemical analysis, and justify- ing, perhaps, the often abused term vitalism. It must not be forgotten that, notwithstanding the simplicity of the single functions, the proto- zoa are units exhibiting a complex of these activities and an harmonious working of them all, no less surely than fish, bird, or mammal. In studying these simple functions it is well not to forget that each belongs in the same category of activities as the functions of much more highly. 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 and Phil