. The biology of the Protozoa. Protozoa; Protozoa. 528 BIOLOGY OF THE PROTOZOA by Schaiidinn (1904) is separated from "female" chromatin, the balance between the two being established by union of the wandering and the stationary pronuclei. Such an hypothetical balance would be maintained if there were no interchange of pronuclei and the third division does not take place, a condition realized in what Woodruff and Erdmann (1914) called endomixis (see p. 540). Experimental evidence leading to definite conclusions has not yet been advanced. Calkins (1921) made an attempt in this directi
. The biology of the Protozoa. Protozoa; Protozoa. 528 BIOLOGY OF THE PROTOZOA by Schaiidinn (1904) is separated from "female" chromatin, the balance between the two being established by union of the wandering and the stationary pronuclei. Such an hypothetical balance would be maintained if there were no interchange of pronuclei and the third division does not take place, a condition realized in what Woodruff and Erdmann (1914) called endomixis (see p. 540). Experimental evidence leading to definite conclusions has not yet been advanced. Calkins (1921) made an attempt in this direction by cutting conjugating pairs of Urolephis vwbilis in such a way that. Fig. 219.— Uroleptus mobilis, conjugation. The interchange of pronuclei, preceded by a characteristic "attraction ; (After Calkins.) :>ach the two migrating pronuclei were removed while the two individ- uals, now separated, possessed only the stationary pronuclei (Fig. 220). These individuals were then followed in cultures, the process of reorganization was completed, the cells regenerated perfectly, and in successful issues, normal rejuvenescence and a typical life history resulted. The crucial point, so far as the present matter is concerned was not determined, viz., from what elements were the new macro- and micronuclei derived? Did the stationary pro- nucleus in its "imbalanced" condition give rise to the new nuclear elements as it would ha^e done were it an amphinucleus? Was. 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. Philadelphia, New York, Lea & Febiger
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