. A manual of zoology. Zoology. 4S-i CHORPATA. \-cins. rousistint; of Ciivicrlaii ilncts and iiii^ular and cardinal veins, tlie laucr with growth eiicroacliiiiy; more aiul more into the territory ol lire suhiiiteslinal veiir. The eirculatioir of the lish tvpe umlerL;oes a great moililK-atioii with the loss of gills and the appearanee of pidnioiiarv respiration in the higher vertebrates. Gills and gill eapillaries disappear, aird the hranehial cireulaliori is reduced to arlcrial arclics leading direct from (he \-entral to the dorsal aorta The swim Idadder recei^â ed its Mood froni the hody (s}-
. A manual of zoology. Zoology. 4S-i CHORPATA. \-cins. rousistint; of Ciivicrlaii ilncts and iiii^ular and cardinal veins, tlie laucr with growth eiicroacliiiiy; more aiul more into the territory ol lire suhiiiteslinal veiir. The eirculatioir of the lish tvpe umlerL;oes a great moililK-atioii with the loss of gills and the appearanee of pidnioiiarv respiration in the higher vertebrates. Gills and gill eapillaries disappear, aird the hranehial cireulaliori is reduced to arlcrial arclics leading direct from (he \-entral to the dorsal aorta The swim Idadder recei^â ed its Mood froni the hody (s}-stemie~) circulation, luit with the functioning of the lungs pulmonary arteries and veins come into existence, while the arterial arches in part. Fig. 537.âDiagram of moditication of arterial arclics in \-arious \-cricbr,uc classes. W'liitc, \*essels wliich clcgencrale; cross-lhioil, ^â csscls coiUainiiig arlcrial liU>;>l; tUacI^. vessels c^tntainiiig \cnoiis I'lood. /, Uijinoi: //, t'riiilclcs willi |niliiionar\" rcs]tiralion; ///, Reptiles; /I', Birds un inaiuiiials the left iuslcad of Uic riglit aortic arcli jicrsisls^. ao\ venous aorta of reptiles; ao'-, arterial aorta; arterial trunk; a. />, arches which usually disappear; ad, dorsal aorta; ductus Botalli; k, gill capillaries; />», pulmo- nary artery; 1-4, persistent arterial arches. disappear, in part arc divided between the pulmonary and svstemic circulations (hg. 537). Of the six arches which usually appear in the emliryo, tlie first and secoird, atid tlie fiftli in airimal-e with lungs, usually degenerate. Tlie last arch (4), which e\en in the Dipnoi sujiplies the swim bladder, becomes a [>uhnonary aiicry, the other arches (i and 2) furnish the systemic portionsâ(he dorsal aorta (2] and the carotids supplv- ing the head (i). Since special pulmonary veins, distinct from the svstemic circulation, carry the blood from the lungs to the heart, the heart be- comes divided by a septu
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectzoology, bookyear1912
