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Page:Popular Science Monthly Volume 61.djvu/47

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PSM V61 D047 Process of union of two reproductive cells.png

Fig. 11. Intimate Processes in the Union of Two Reproductive Cells from Photographs of Ascaris, all but b., with an initial magnification of 1,500 diameters, a. A spermatozoon. b. A spermatozoon in the egg very highly magnified, c. Male and female nuclei after assuming the resting stage, d. Male and female nucleus coming out of the resting stage, the chromatic threads assuming definite shape, e. The threads from two nuclei being pulled together. f. A late stage of the same process, g. The completion of the process, h and i. Two eggs in the stage presented by g, but seen from one of the poles of the egg: two of the threads shown in both h and i are derived from the father and the other two from the mother.