NA TURE 



331 



THURSDAY, NOVEMBER 26, 1914. 



THE RESPIRATORY FUNCTION OF THE 

 BLOOD. 



The Respiratory Function of the Blood. By 

 Joseph Barcroft, F.R.S. Pp. x + 320. Cam- 

 bridge University Press, 1914.) Price 185. net. 

 THE title of this book gives but an inadequate 

 idea of the scope of its contents. As the 

 author states in the Preface, it is really an 

 account of his " physiological ventures," and con- 

 sists mainly of the researches undertaken by him- 

 self and his pupils, with slighter references to 

 cognate work by other observers. The wealth of 

 new facts and ideas which are here presented bears 

 striking witness to the important part played 

 in the advance of science by the discovery of a 

 new technique. In practically all the investigations 

 here presented it was necessary to determine the 

 gaseous contents of minute quantities of blood or 

 other fluids, so that the discoveries here made 

 may be said to be the direct outcome of Haldane's 

 invention of a method for the gaseous analysis of 

 small quantities of blood — a method since per- 

 fected and elaborated to such an extent by the 

 author of this book as to be identified with him. 

 Armed with this new technique, he was able to 

 attack a number of capital problems connected 

 v.ith the behaviour of oxygen in the blood, its 

 uptake in the lungs, and the conditions of its 

 utilisation by the tissues, with an ease and 

 accuracy which previously was impossible. 



This book, however, is not a mere reprint of 

 Barcroft 's physiological papers. In presenting 

 his results, he wisely abandons the chronological 

 for a logical order. In the first part he begins 

 with a description of the physical and chemical 

 characters of haemoglobin and the determination 

 of its combining power for oxygen in relation to 

 its iron content. The constancy of the figures 

 obtained in his latest experiments for oxygen 

 capacity and iron content is regarded by the author 

 as almost convincing proof that the combination 

 is chemical in the strict sense of the term. He 

 then discusses the oxidation curve of oxyhaemo- 

 globin and the influence of temperature, electro- 

 lytes and acids on the curve. An important result 

 arrived at is that the variations which have been 

 described in the dissociation-curves in the blood 

 of different animals may be ascribed to differ- 

 ences in the salt-content of the blood-corpuscles, 

 which determine varying degrees of the aggrega- 

 tion of the colloidal haemoglobin molecule. 



In part ii. he proceeds to discuss what signi- 

 ficance these facts have for the normal life of the 

 animal. The question of the factors which deter- 

 XO. 2352, VOL. 94] 



mine the supply of oxygen to the tissues during 

 rest and activity, involves difficult physiological 

 experimentation on the exchange of gases be- 

 tween tissues and blood in voluntary muscle, 

 heart, adrenals, pancreas, kidney and liver. 

 From these results we are led on to another series 

 in which the oxygen intake of the tissues is used 

 as a criterion of the activity of the tissue-cells. In 

 this way he is able to throw a welcome light on 

 the nature of some of the phases of renal activity 

 — activity of the cells being assumed as respons- 

 ible for urinary' formation when an increased flow 

 of urine is associated with an increased uptake of 

 oxygen by the kidney. A chapter on the meta- 

 bolism of the blood itself (which, except in 

 abnormal circumstances, is shown to be negligible) 

 is followed by an account of the mechanism by 

 means of which the supply of oxygen to the tissues 

 may be regulated according to their needs. 

 Prominent among these mechanisms is the local 

 production of lactic acid and possibly other meta- 

 bolites, which not only have a vaso-dilator action, 

 so increasing the blood-flow through the part, but 

 also, by their action on the dissociation-curv'e of 

 haemoglobin, favour the transfer of oxygen from 

 oxyhaemoglobin to the tissues. 



In the next chapter he describes a bold attempt 

 made by him in conjunction with Verzar to deter- 

 mine the head of pressure driving oxygen from 

 the blood to the tissues, using as his criterion 

 the effect of variations in the oxygen-supply on 

 the amount of this gas taken up by the tissues. 



Under normal conditions, the blood has only a 

 certain time to take up oxygen in the lungs and 

 to give up oxygen in the tissues, viz. the duration 

 of its transit through the capiUaries of lungs and 

 tissues respectively. An investigation of the rates 

 of combination and dissociation of oxygen and 

 haemoglobin enables the author to show that the 

 physical conditions which determine the form of 

 the dissociation-curve outside the body are suffi- 

 cient to account for the changes taking place 

 within the body. This investigation naturally 

 leads on to a discussion on the much debated 

 question as to the mechanism of the uptake of 

 oxygen in the lungs. A very impartial account 

 is given of the views and investigations of Bohr, 

 Haldane, Krogh, and Hartridge. His final con- 

 clusion is in favour of the view according to which 

 the process is determined by the physical condi- 

 tions existing in the lungs, though he points 

 out that the question cannot be regarded as finally 

 settled until the results obtained by Haldane and 

 others on Pike's Peak have been reinvestigated by 

 Hartridge 's methods or have received some ade- 

 quate explanation. 



The third part of the work deals with the dis- 



O 



