96 



VERTEBRATE RESPIRATION 



(a) 



7o Saturation 



100 7cr^^ 



d' XDOG 80m.m. C.O2 



507. 



m. Hg. 



PERCH 

 80m.m. CO2 



100 200 300 ^00 500 600 700 

 m.m. Hg. 



10 20 30 40 50 

 mm. Hg. 



1007or Umb.v. 



Ut.art. 



Umb. A/ ^ 



^'^/^<.Cut.v. mno/. , PH7A^pH70.38m.m.Hg.CO, 



;P^_^_°_ _^_pH 6-3j 76m.m. CO2 



SHEEP (80 days) 

 AOm.m. Hg. 



507o 



20 AO 60 80 100 

 i.m. Hg. 



(c) 



BLACK 

 GROUPE R 



LONG-NOSED EEL 



SOAts. 100 



Oxygen pressure 



(d) 



^ y^ 



250 



Fig. 27. 



Oxygen dissociation curves of some vertebrate bloods, (a) Fish and 

 dog bloods at different CO2 tensions. The two tensions are approxi- 

 mately those found in the tissues and lung of a dog, so that the actual 

 curve for the operation of haemoglobin in the body lies between 

 them, (b) Protopterus showing only a slight Bohr shift, (c) Maternal 

 and foetal haemoglobin of a sheep. The O2 tensions in the umbilical 

 vein and artery, uterine vein and artery are indicated, (d) Shows the 

 way in which fish bloods from deep water species (e.g., black-grouper) 

 does not become 100 % saturated in the presence of CO2 even at very 

 high pressures. In other species (long-nosed eel, full lines) the blood is 

 fully saturated at the depths where the animal lives (indicated by 

 blocks), even in the presence of high CO 2 tensions, (b, after Fish, G. 

 R.: /. exp. Biol. Vol 33, 1956; c, after Barron, D. H. and Meschia, 

 G., Cold Spr. Harbor Symp. Vol. 1 9, 1 954 ; d, after Scholander, P. F. 

 and van Dam, L. Biol. Bull. Vol. 197, 1954.) 



