August 23, 1888] 



NATURE 



399 



the Itany and that of the Camopy.. Starting by the Maroni, 

 M. Coudreau, after having gone up the Itany and explored the 

 region which it waters, came down to the coast by Maronimi- 

 ( rique, which is a very large tributary of the Maroni River. M. 

 Cooareatr is the first Frenchman who has passed a consecutive 

 winter and summer in theTumuc-Humac Mountains, and though 

 lie did not himself suffer very much from the effects of the 

 expedition, the same cannot be said of his companions, as the 

 Only European who accompanied him was brought near to death's 

 : by fever, from which most of the natives also suffered. M. 

 Ireau escaped with nothing worse than rheumatism, and he 

 that the climate of the Western Tumuc-Humac is not bad. 

 The result of 1200 observations taken by him puts the mean 

 temperature at 70 , and the country is a magnificent one ; but 

 the difficulty of reaching it is very great owing to the uncertainty 

 of communication with the coast. M. Coudreau and his com- 

 panions, when they had exhausted their provision-, had to go 

 and live out in the open with the Indians, leading the same kind 

 of existence, and depending for food upon the game, fish, and 

 fruit that they could shoot, fish, and gather. For eight months 

 M. Coudreau lived the regular native life, and he had become 

 su accustomed to it that he was very popular with the Rucuy- 

 ennes, whose language he had learned to speak, and he induced 

 the pamenchi (captain) of the tribe and four of his lieutenants to 

 accompany him to Cayenne, where their arrival created a great 

 sensation, as the people of the town did not believe in their 

 existence. M. Gerville-Reache, the Governor of the colony, 

 received them with great hospitality, and made them several 

 presents. The most important fact brought out by M. Coudreau 

 is the existence in Upper Guiana, which is acknowledged French 

 territory, of sixteen new Indian tribes, forming a group of at least 

 20,000 persons ; and these Indians are not, as was supposed, 

 mere nomads, living upon the produce of th?ir guns and fishing- 

 nets, but are sedentary in their habits, and have attained a certain 

 degree of civilization. M. Coudreau is about to start on a fresh 

 expedition to the Appruague and the Oyapack, and does not 

 expect to get back before next spring. 



THE GASES OF THE BLOOD} 



II. 



piIE next step was the discovery of the important part per- 

 formed in respiration by the colouring matter of the red blood 

 corpuscles. Chemically, these corpuscles consist of about 30 or 

 40 per cent, of solid matter. These solids contain only about 1 

 per cent, of inorganic salts, chiefly those of potash ; whilst the 

 remainder are almost entirely organic. Analysis has shown that 

 100 parts of dry organic matter contain of haemoglobin, the 

 colouring matter, no less than 90-54 per cent. : of proteid sub- 

 stances, 8-67 ; of lecithin, 0-54; and of cholesterine, 0*25. The 

 colouring matter, haemoglobin, was first obtained in a crystalline 

 state by Funke in 1853, and subsequently by Lehmann. It has 

 been analyzed by Hoppe-Seyler and Carl Schmidt, with the 

 result of showing that it has a perfectly constant composition. 

 Hoppe-Seyler's analysis first appeared in 1868. Ic is now well 

 known to be the most complicated of organic substances, having 

 a formula, as deduced, from the analyses I have just referred to, 

 by Preyer (1871), of 



0600"96oNi54FeS 3 179 . 



In 1862, Hoppe-Seyler noticed the remarkable spectrum pro- 

 duced by the absorption of light by a very dilute solution of 

 blood. Immediately thereafter, the subject was investigated by 

 Prof. Stokes, of Cambridge, and communicated to the Royal 

 Society in 1864. If white light be transmitted through a thin 

 stratum of blood, two distinct absorption bands will be seen. 

 One of these bands next D is narrower than the other, has more 

 sharply defined edges, and is undoubtedly blacker. " Its centre," 

 as described by Dr. Gamgee ("Physiological Chemistry," 

 p. 97), "corresponds with wave-length 579,- and it may 

 conveniently be distinguished as the absorption band, o, in 

 the spectrum of oxyhemoglobin. Tne second of the absorption 

 bands— that is, the one next to E — which we shall designate 

 0, is broader, has less sharply defined edges, and is not so 



1 Address to the British Medical Association at its annual meeting at 

 Glasgow. Delivered on August 10 in the Natural Philosophy class-room 

 University ofGlasg ,w, by John Gray McKendrick, M.D., LL.D., F.R.SS.L' | 

 a ?4, E- ' F-RC.P.E., Professor of the Institutes of Medicine in the University 

 of Glasgow. Continued from p. 382. I 



2 Dr. Gamgee gives the measurements of the wave-lengths in millionths ' 

 not in ten-mil lionths of a millimetre. ( 



dark as o. Its centre corresponds approximately to wave- 

 length 553 - 8. On diluting very largely with water, nearly 

 the whole of the spectrum appears beautifully clear, except 

 where the two absorption bands are situated. If dilution be 

 pursued far enough, even these disappear ; before they disappear 

 they look like faint shadows obscuring the limited part of the 

 spectrum which they occupy. The last to disappear is the band 

 a. The two absorption bands are seen most distinctly when a 

 stratum of 1 cm. thick of a solution containing 1 part of haemo- 

 globin in iooo is examined ; they are still perceptible when the 

 solution contains only 1 part of haemoglobin in 10,000 of water. ' r 

 Suppose, on the other hand, we begin with a solution of blood! 

 in ten times its volume of water ; we then find that such a solu- 

 tion cuts off the more refrangible part of the spectrum, leaving 

 nothing except the red, "or, rather, those rays having a wave- 

 length greater than about 600 millionths of a millimetre." On. 

 diluting further, the effects, as well described by Prof. Gamgee, 

 are as follows : — "If now the blood solution be rendered much 

 more dilute, so as to contain 8 per cent, of haemoglobin, on 

 examining a spectrum 1 centimetre wide the spectrum becomes 

 distinct up to Fraunhofer's line D (wave-length 589) — that is, the 

 red, orange, and yellow are seen, and in addition also a portion of 

 the green, between b and F. Immediately beyond D, and between 

 it and />, however (between wave-lengths 595 and 518), the 

 absorption is intense. " 



These facts were observed by Hoppe-Seyler. Prof. Stokes 

 made the very important contribution of observing that the spec- 

 trum was altered by the action of reducing agents. Hoppe-Seyler 

 had observed that the colouring matter, so far as the spectrum 

 was concerned, was unaffected by alkaline carbonates, and caustic 

 ammonia, but was almost immediately decomposed by acid--, and 

 also slowly by caustic fixed alkalies, the coloured product of 

 decomposition being hnsmatin, the spectrum of which was known. 

 Prof. Stokes was led to investigate the subject from its physio- 

 logical interest, as may be observed on quoting his own words 

 in the classical research already referred to. " But it seemed to 

 me to be a point of special interest to inquire whether we could 

 imitate the change of colour of arterial into that of venous blood, 

 on the supposition that it arises from reduction. 1 ' 

 He found that — 



"If to a solution of proto-sulphate of iron enough tartaric 

 acid be added to prevent precipitation by alkalies, and a small 

 quantity of the solution, previously rendered alkaline by either 

 ammonia or carbonate of soda, be added to a solution of blood, 

 the colour is almost instantly changed to a much more purple- 

 red as seen in small thicknesses, and a much darker red than 

 before as seen in greater thickness. The change of colour which 

 recalls the difference between arterial and venous blood is striking 

 enough, but the change in the absorption spectrum is far more 

 decisive. The two highly characteristic dark bands seen before 

 are now replaced by a single band, somewhat broader and less 

 sharply defined at its edges than either of the former, and occupy- 

 ing nearly the position of the bright band separating the dark 

 bands of the original solution. The fluid is more transparent 

 for the blue and less so for the green than it was before. If the 

 thickness be increased till the whole of the spectrum more re- 

 frangible than the red be on the point of disappearing, the last 

 part to remain is green, a little beyond the fixed line l>, in the case 

 of the original solution, and blue some way beyond F, in the case 

 of the modified fluid." 



From these observations, Prof. Stokes was led to the important 

 conclusion that — 



"The colouring matter of blood, like indigo, is capable of 

 existing; in two states of oxidation, distinguishable by a differ- 

 ence of colour and a fundamental difference in the action on the 

 spectrum. It may be made to pass from the more to the less 

 oxidized by the action of suitable reducing agents, and recovers 

 its oxygen by absorption from the air. " 



To the colouring matter of the blood Prof. Stokes gave the 

 name of cruorine, and described it in its two states of oxidation. 

 as scarlet cruorine and purple cruorine. The name haemoglobin, 

 given to it by Ploppe-Seyler, is generally employed. When, 

 united with oxygen it is called oxyhemoglobin, and when in, 

 the reduced state it is termed reduced haemoglobin, or simply 

 haemoglobin. 



The spectroscopic evidence is, therefore, complete. Hoppe- 

 Seyler, Hiifner, and Preyer have shown also that pure crystallized 

 haemoglobin absorbs and retains in combination a quantity of 

 oxygen equal to that contained in a volume of blood holding the 

 same amount of haemoglobin. Thus, 1 gramme of hemoglobin 

 absorbs 1*56 cubic centimetre of oxygen at o° C. and 760 milli- 



