. A text-book of comparative physiology for students and practitioners of comparative (veterinary) medicine . 5 , cr ^ co ^ C o a cd g ° o ^cti a 5-5 1 ascs^aog^-g ,xji e^ ■-, 1 aJ o o CM 03 O. 60^ 5 .$ = 5 S ^ ¥? S S be 0 W 3 ,- bo H 2 =3 „co „ 0 = s cd a t- lc a Si „s 3 s .bp > 2 . « s °J 3 C3i o , ft a s » So B ft bo iO 3 n) b0W W rg CD ^ Ti . » g 2 fe a -a « o « - « bo 5 I § ^ Z2 — 5 0 2 ^ CO ^O^H-r-HCD la4^ I ?r ^ i K C S s e , i at o cd a to 71 j, .a P s .sj • .SP 5 2 .£P SP w fe .a orj ^ cd &fe°fe £ £I^fe S .. 1* ^ sj to ~ hV a cd , d d cs ■s 5 5 3 =e -8 £. &( REPRODUCTION. 67 eraliz
. A text-book of comparative physiology for students and practitioners of comparative (veterinary) medicine . 5 , cr ^ co ^ C o a cd g ° o ^cti a 5-5 1 ascs^aog^-g ,xji e^ ■-, 1 aJ o o CM 03 O. 60^ 5 .$ = 5 S ^ ¥? S S be 0 W 3 ,- bo H 2 =3 „co „ 0 = s cd a t- lc a Si „s 3 s .bp > 2 . « s °J 3 C3i o , ft a s » So B ft bo iO 3 n) b0W W rg CD ^ Ti . » g 2 fe a -a « o « - « bo 5 I § ^ Z2 — 5 0 2 ^ CO ^O^H-r-HCD la4^ I ?r ^ i K C S s e , i at o cd a to 71 j, .a P s .sj • .SP 5 2 .£P SP w fe .a orj ^ cd &fe°fe £ £I^fe S .. 1* ^ sj to ~ hV a cd , d d cs ■s 5 5 3 =e -8 £. &( REPRODUCTION. 67 eralizecl as consisting of division and segregation, followed byaggregation. The subdivision (segmentation) of the cell, after the quies-cence referred to, again commences, but in a plane at rightangles to the first, from which four spheres result, again to befollowed by the resting stage. The process continues in thesame way, so that there is a progressive increase in the number. Fig. 05.—The cleavage of a frogs egg (10 times enlarged). A, the parent-cell; B, thefirst two cleavage-cells; cells; D, 8 cells (4 animal and 4 vegetative); E. 12cells (8 animal and 4 vegetative); F, 16 cells (8 animal and 8 vegetative); G, 24cells (1(5 animal and 8 vegetative); H, 32 cells: /. 48 cells; A. 04 cell^: L. 96 eleav-age-cclls; .]/, mo cleavage-cells (128 animal and 32 vegetative). (Haeckel.) of segments, at least up to the point when a large number hasbeen formed. This is rather to be considered as a type of one 68 COMPARATIVE PHYSIOLOGY. form of segmentation than as applicable to all, for even atthis early stage differences are to be noted in the mode of seg-mentation wbich characterize effectually certain groups of ani-mals ; but in all there is segmentation, and that segmentationis rhythmical. Segmentation results in the formation of a multicellularaggregation which, sooner or later, incloses a central cavity(segmentation cavity, blastocele). Usually this c
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishernewyo, bookyear1890
