HISTORY AND ANATOMY OF THE GOLDFISH 



tion takes place after the eggs are discharged, their outline then assuming 

 a more spherical form, whereby the spermatozoa are drawn into the ova 

 through minute orifices and the egg fertilized. 



The circulation of the blood is induced by a branchial or respiratory 

 heart consisting of two cavities, an auricle and a ventricle. Fig. 5. The 

 venous blood, coming from the liver and the body generally, is taken 



through the vena cava into the auricle and pro- 

 pelled into the ventricle, from which arises an 

 aortic arch, dilated at the base into a cavity, the 

 bulbus arteriosus, which has transverse rows of 

 valves, and is covered with muscular fibres for 

 rhythmical contraction. The blood is driven by 

 the ventricle through the branchial artery to the 

 gills where it is distributed by means of the bran- 

 chial laminse and subjected to the action of the 

 aerated water and thereby oxygenated. The 

 water is taken in at the mouth, forced to the 

 branchia by muscular action, passed over the gills, 

 deoxydized and then emitted from the gill slits, 

 or opercular appertures, on each side of the neck. 

 These gill slits" are closed in front and covered 

 by the operculum bones connected by bony spines 

 with the hyoid arch supporting the branchiostegal 

 membrane. The aerated blood is not returned 

 to the heart, as in higher forms of animals, but is 

 driven from the branchia through all parts of the 

 body by the action both of the heart and the 

 contractions of the voluntary muscles; that is, 

 the arterial blood returned from the gills is pro- 

 pelled through the systemic vessels of the body 

 without being first sent back to the heart. The 

 oxygen thus consumed is not that which forms 

 the chemical cons'tituent of water (H2O) but that 

 contained in the air which is dissolved or in sus- 

 pension in the water. Fishes transferred to water 

 devoid of air are speedily suffocated, but gold- 

 fishes are of low vitality and their absorption of 

 oxygen is comparatively small, as compared with 

 others; this, however, being also characteristic of 

 all Stillwater fishes in greater or lesser degree. 



2 3 



FIG. 5 — Diagram of the Blood cir- 

 culatory systems of Fishes, Rep- 

 tiles and Mammals. 



No. I — Diagram of a fish. 

 a' Auricle, receiving venous blood 

 trom the body. 



V Ventricle. 

 a Bulbus artoriosus, at the base of 



the branchial artery. 

 ba Branchial artery, carrying the 



venous blood to the gills. 

 I- Aorta, carrying the arterial blood 



to all parts of the body. 

 g. Gills 

 No. 2 — Diagram of a Reptile. 

 a Right auricle, receiving venous 



blood from the body. 

 a^ Left auricle, receiving arterial 



blood from the lungs. 



V Arterio-venous ventricle, con- 

 taining mixed blood, which is 

 driven by the pulmonary artery 

 (p) to the lungs, and by the 

 aorta (o) to the body. 



The Venous system is left light, 

 the arterial system is black, and 

 vessels containing mixed blood 

 are cross-shaded. 

 No. 3 — Diagram oi a Mammal. 

 a Right auricle. 



V Right ventricle. 

 p Pulmonary artery, carrying ven- 

 ous blood to the lungs, 



fv Pulmonary veins, carrying arte- 

 rial blood from the lungs. 



a' Left auricle. 



v^ Left ventricle. 



h Aorta, carrying arterial blood to 

 the body. 



c Vena cava, carrying venous 

 blood to the heart. 

 The arterial system is left white 

 and the venous system is black. 



