. A text-book of animal physiology [microform] : with introductory chapters on general biology and a full treatment of reproduction, for students of human and comparative (veterinary) medicine and of general biology. Physiology, Comparative; Veterinary physiology; Physiologie comparée; Physiologie vétérinaire. Fio. 68.—Karir etagee of Msmentation of a moUtiak, SlyHa vMdia (drawn from the IlTlng esg). A, oosperm in ataie of reat after the eztraoion of the pcdar cells; B, the nuoleolua atone baa divided; O, the nucleus is diyiding; D, the nucleus, as such, nas disappeared, first segmentation fur
. A text-book of animal physiology [microform] : with introductory chapters on general biology and a full treatment of reproduction, for students of human and comparative (veterinary) medicine and of general biology. Physiology, Comparative; Veterinary physiology; Physiologie comparée; Physiologie vétérinaire. Fio. 68.—Karir etagee of Msmentation of a moUtiak, SlyHa vMdia (drawn from the IlTlng esg). A, oosperm in ataie of reat after the eztraoion of the pcdar cells; B, the nuoleolua atone baa divided; O, the nucleus is diyiding; D, the nucleus, as such, nas disappeared, first segmentation furrow appears; E, later stase; F, ofiqierm divided into two distinct seKmentation spheres, the clear nuclear space m the center of the aster of granules is growbiflr larow; O, resting stan of appressed two spheres; H, I, similar stages in the produraon of four spheres; K, larmatfDn of eight-celled stage. (Haddon.) character as nuclei and nucleoli, are replaced by asters (polar stars), which seem to arise in the protoplasm of the body of the cell, and which are in close juxtaposition at first, but later separate, the oosperm becoming amoeboid in one region at least. A groove, which gradually deepens, appears on the sur- face, and finally divides the cell into two halves, which at once become flattened against each other. The nucleus may again be recognized in the center of each polar star, while a new nu- cleolus also reappears within the nucleus, when again a brief period of rest ensues. In the division and oioiination of the nucleus, when most complicated (karyokinesis), the changes may be generalized as consisting of division,and segregation, followed by aggregation. The subdivision (aegmentaiion) of the cell, after the quies- cence referred to, again commences, but in a plane at right angles to the first, from which four spheres result, again to be followed by the resting stage. The process continues in the. same way, so that there is a progressive increase in the num- be
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Keywords: ., bookauthormillswes, bookcentury1800, bookdecade1880, bookyear1889
