CHEMICAL BASIS OF THK ANIMAL ISnpy. 



tion before applying IVttenkofer's test. This is effected either by 

 precipitation with basic It-ad acetate or extraction with alcohol or 

 chloroform. 1 



THE COLoriMNC MATTKKS AND I'KIMENTS 

 ()K THK ANIMAL BODY 



ILEMOGLOBIN AXI> ITS DKl:l\ATI\ 



1. Haemoglobin. 2 This is the well-known constituent of the 

 red corpuscles to which tin- dark colour ot' tin- lilooil from an 

 a>phyxiated animal is due. It is also present to a less and 

 .somewhat variable amount in ordinary venous Mood, in proem -. 

 f correspondingly variable amounts of the coniDounoT which it 

 forms ;en, namely oxy-ha-moglobin. In iiornTal arterial 



blood it is probably present in mere traces, if at all, since here its 

 athnities for oxygen arc completely satisfied to form oxy-ha-iuo- 

 globin. Hai'inoglobin is chiefly ot interest as an oxygen-carrier or 

 respiratory pigment, in virtue of the ease with whieh it ah-orbs 

 and unites in loose combination with oxygen when meivh 

 posed to this gas. and again gives it up when brought into rela- 

 tionship with the oxygen-free tissues of the body. The conditions 

 and phenomena of this fixation and liberation of oxygen by luemo- 

 glol.in have been very fully investigated ; the fundamentally im- 

 portant facts in connection with it have already been stated in 

 some detail in an earlier part of tlii- work ;j ."43 et seq.), so that 

 it is now only necessary to add ><me farther detail* of ha-moglobin 

 more purely chemical characi 



Owing to the ea-e and avidity with which lui-moglobin unites 

 with oxygen to form the distinct and stable comiiound known as 

 oxy_-ha-nio^li>biii. it< investigation i- atTended with considi-rable 

 experimental ditlii'iilties . hence our knowledge of it as a chemi- 



ibatanoe is on the whole le-< complete than is that ol' 

 h.eino^lobin. Ha'inoglobin iriay be obtained in a crystalline 

 but with some considerable difficulty owing to its extreme 

 solubility in water. The crystaK may be prepared by sealing up 



a concentrated aqueous solution of oxy-htemoglobin in gla-^ tubes 



from which, it iv. all remaining air is displaced by hydro- 



gen : on prolonged standing all tip disappear- during the 



putrefactive reduction which en-u.-. and finally, more readily on 



exposure to a low temperature, crystals of ha-mogiohjn make their 



r il.-t.-iiN I! - i i>hif.-initli. ' I !<H3, 8. 399, 



ami NiMiliatn-r 11. \'M^>-|, .!.///,> ./. // ui. . 



-' Tin- Mii^le name hmncwlobin i" n'l li- : liat i- i 



ami usually ralli-il r'.iir .,! ' liii-inncloliiu, us distinrt fnun 

 a<loption nf tin- name as li.-n- oed iff both simpler ami tii>n- I 



First .lcs.Til-.| l.y Kulm,-. Vio'li..*'.* An-h. M. X\\M. (!'.). S. 4*3. 



