LTOA rLTRTN'O THE ANTIOllIOR ABDOMINAL VEIN IN INDIAN TOAD. 441 



20. On rioiue Results of Ligiitiiriiig the Anterior Abdominal 

 Vein in the Indian Toad {Biifo stomaticus Lutken). 

 By W. N. F. Woodland, D.Sc. (London), F.Z.S., 

 Indian Edacational Service, Senior Professor of Zoology, 

 Mair Central College^ Allahabad, U.P., India. 



[Received June 1, 1920 : Read October 19, 1920. J 

 (Text-figure 1.) 



Preliminary Statement. 



Most of tlie lower Vertebrata differ from the Mammalia in 

 that the liver has conveyed to it a quantity of venous lilood which 

 has traversed the tissues of the legs and pelvic region, in addition 

 to the venous blood wdiich, as in Mammals, is derived from the 

 gut-walls and contains the digested food products. This fact that 

 in the lower Vertebrata the liver receives a portion of ordinary 

 non-gut venous blood has not received the attention which its 

 possible significance deserves. tSo far as I know*, only one 

 author has ever offered an explanation, and this solely appertained 

 to the coccygeo-mesenteric vein of Birds. Owen in 1841 f made 

 the following observations : " The venous system of the kidneys 

 is so arranged in birds tliat the blood can be distributed either to 

 the portal system by the mesenteric vein \i.e. the blood brought 

 to the kidneys by the femoral veins can ^ow posteriorly through 

 the substance of the kidneys in the so-called hypogastric veins 

 :ind so enter the coccygeo-mesenteric vein], or to the pulmonary 

 system by the vena cava and right side of the heart, according to 

 the degree of rapidity with which the pulmonary or portal 

 systems of veins are respectively supplied, or in other words, 

 according to the activity with which the circulation in each 

 of these systems may be going on at two different periods .... 

 Tliis disposition has been erroneously supposed to indicate that 

 the urine was secreted from the venous blood in birds, as 

 in reptiles and fishes; but the end attained by the venous 

 anastomoses in question bears a much closer relation to the 

 peculiar necessities and habit of life of the bird, and, so far as 

 I know, has not hitherto been explained. There is no class of 

 animals in which there may be, at any two brief and consecutive 

 periods of existence, a greater difference in the degree of eneri>y 

 and rapidity wuth which the respiratory functions ai-e performerl 

 than in birds. When the bird of prey, for example, stimulated 

 by a hungry and an empty stomach, soars aloft and sweeps the 

 air in quest of food, the muscular energies are then strained to 

 the utmost, the heart l)eats with the most forcible and rapid 



* The author has not had access to hterature in India. 



t " On the Anatomy of the Southern Apteryx," Trans. Zool. Soc. London 

 vol. ii. 1841. 



Prog. Zool, Soc —1920, No. XXX, 30 



