334 



ZOOLOGY 



blood emerges, and, slipping o^•er the entrance to the now filled 

 pulmonary arteries, goes on to the dorsal aorta and the organs 



FiG. 314. — ^ Thf hoart of the frog with the <'avitirs hiifl open. Blood 

 oiiters from the venous sinus into the right aurieh"-, r.ini, at s-.au.op. The 

 right auriflo is completely separated from the left (I. mi) liy a partition 

 (spt.aur). Both auricles open by the same aperture, guarded by two 

 valves (au.v.v) into the ventricle, vl. The left auricle receives the pul- 

 monary veins at jiid.v. The exit of blood from the ventricle is guarded 

 l)y valves at v, and its further path directed b>' a \-aK'e at l.v, into the 

 right and left pulmonary arteries, piil.ruJr. and '■,'','■', into the arteries 

 going to the general trunk, .s//.s7./r and /', /'', and into the arteries going 

 to the liead, c'lr.lr, with its eari.itiil artery {citr.tt) and so-called gland 

 {car.gl) ; and with its tongue branch (bj-d)- 



of the trunk ; finally the purest Mood, which is the last to leave 

 the ventricle, passes on to the last pair of vessels, which go to 

 the brain, where it is most needed. The fact that the trunk 



