. The biology of the Protozoa. Protozoa; Protozoa. NUCLEI AND KINETIC ELEMENTS 117. n.h-. 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. Philadelphia, New York, Lea & Febiger

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RMRHK4J7–. The biology of the Protozoa. Protozoa; Protozoa. NUCLEI AND KINETIC ELEMENTS ^ /^^ % %. ^. 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. Philadelphia, New York, Lea & Febiger

RMRHK4GN–. The biology of the Protozoa. Protozoa; Protozoa. NUCLEI AND KINETIC ELEMENTS 73. % ^. 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. Philadelphia, New York, Lea & Febiger

RMRHK496–. The biology of the Protozoa. Protozoa; Protozoa. NUCLEI AND KINETIC ELEMENTS 85 Z>. 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. Philadelphia, New York, Lea & Febiger

RMRHK1Y2–. The biology of the Protozoa. Protozoa; Protozoa. MORPHOLOGY AND TAXONOMY OF MASTIGOPHORA 293 sets of what are ol^viously unit aggregates of nuclei and kinetic elements (karyoniastigonts and akanomastigonts of Janicki). The great majority of forms included here are parasitic and most of them are simple with one cytostome if any (Tribe Monozoa). The kinetic elements are highly developed much more so than in free-living t;y^es. In a small number of genera which are usually grouped as the Order Distomatida (Klebs), the cytostome is double and the organisms are bilaterally symmetrical. In the maj

RMRHK405–. The biology of the Protozoa. Protozoa; Protozoa. NUCLEI AM) KINETIC ELEMENTS 101 evidence of constructive metabolic activities in the cell. For these reasons I believe, with Kofoid, that the term "parabasal body" expresses the relationships and functional activities of the so-called "kinetonucleus" much better than does the latter term and should take its place in literature dealing with the Protozoa. /0^ •I? 0m.... h--. mM^-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appeara

RMRHK4A9–. The biology of the Protozoa. Protozoa; Protozoa. NUCLEI AND KINETIC ELEMENTS 83 definite body, the substance of which forms the pole plates. Hertwig (1898) and Doflein (1916) assume that they are formed from the linin substance of the nucleus. On this assumption the pole plates might be interpreted as hyaline aggregates of the linin reticulum of the nucleus, indeerl, the hyaline and homogeneous appearance of the pole plates is suggestive of amoeba ectoplasm. ^Yith our present knowledge I am inclined to agree with this interpretation of pole plates and to regard Paramecium caudatum, with othe

$. The biology of the Protozoa. Protozoa; Protozoa. NUCLEI AND KINETIC ELEMENTS 67 plasmic substances under the action of the kiHin^ fluids and are ahvays to be interpreted as artefacts. The chromidiosomes are suspended in, and held in place by, the linin reticuhnn, which in some cases is extremely delicate and difficult to see, while the inter- alveolar spaces are filled with fluid enchylema {e. g., Arcella vukjaris). In other cases, owing to the suspension of very fine chromomeres, the outlines of the intranuclear alveoli are characteristically distinct {e. g., Acineta grandis). In most massi Stock Photo$

RMRHK4JN–. The biology of the Protozoa. Protozoa; Protozoa. NUCLEI AND KINETIC ELEMENTS 67 plasmic substances under the action of the kiHin^ fluids and are ahvays to be interpreted as artefacts. The chromidiosomes are suspended in, and held in place by, the linin reticuhnn, which in some cases is extremely delicate and difficult to see, while the inter- alveolar spaces are filled with fluid enchylema {e. g., Arcella vukjaris). In other cases, owing to the suspension of very fine chromomeres, the outlines of the intranuclear alveoli are characteristically distinct {e. g., Acineta grandis). In most massi

RMRHK3KW–. The biology of the Protozoa. Protozoa; Protozoa. NUCLEI AND KINETIC ELEMENTS 119 presumably cliAides to form the daughter plates as shown in Schaudinn's well-known figure, or to division figures like that of Centropyxis aculeata. Another widely distributed type of division figure is derived from vesicular nuclei in which the chromatin is not contained in one or more endosomes but is distributed peripherall' about the nucleus where it usually forms a distinct chromatin reticulum. Such nuclei usually contain an endosome which may be the most conspicuous structure of the nucleus. In Amoeba cry

RMRHK4KN–. The biology of the Protozoa. Protozoa; Protozoa. NUCLEI AND KINETIC ELEMENTS 65 similar size and are densely packed throughout the entire nucleus, giving a characteristic appearance after staining. They are widely distributed in Dinoflagellata, Ciliata and Suctoria, but there is con- siderable variation in their density in different species, especially in the Infusoria. In some of the micronuclei {e. g., Paramecium caudaUim, Euplotes patella, etc.), the chromidiosomes are so tightly packed as to give them, more than any other type of protozoon nucleus, the aspect of a spermatozoon head (Fig.

RMRHK4EA–. The biology of the protozoa. Protozoa; Protozoa. THE FUNDAMENTAL ORGANIZATION 61 finally, there is no evidence at all of kinetic elements in resting nuclei, but collections of homogeneous substance (karyolymph) are present at the poles of the nucleus during division (pole plates). 1. Large Homogeneous Endobasal Bodies. — In this type the endo- basal body is conspicuous by its large size and homogeneous struc- ture. It was first described by Kenten (1895) in Euglena viridis and was early recognized as a kinetic element connected with nuclear division as attested by the names intranuclear cent

RMRHK4RK–. The biology of the Protozoa. Protozoa; Protozoa. NUCLEI AND KINETIC ELEMENTS 57 able that some functions are possible by virtue of the physical prop- erties of a definite, but permeable, nuclear membrane, and as in the tissue cells of IVIetazoa, it is this type of membrane-bound nucleus that we find in the vast majority of Protozoa. In their resting stages the nuclei of Protozoa present a bewildering variety of forms and structures, differing in this respect from the. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability -

RMRHK43G–. The biology of the Protozoa. Protozoa; Protozoa. NUCLEI AND KINETIC ELEMENTS 89 A modification of this mode of origin of the cytoplasmic kinetic element is shown by Parapolytoma saiurna according to Jameson (1914) and by Oxyrrhis marina (Hall, 1925). In these cases the old flagella and their basal bodies are said to degenerate and dis- appear prior to, or during, nuclear division. An intranuclear endo- basal body which is concealed within an endosome during vegetative. Fig. 44.—Oxyrrhis 7})arina; details of nucleus, centriole, and paradesmose. (After Hall.) life, first divides, its daughter

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