GLOBULIN. 367 



assumes a milky turbidity, and at 93 separates as a globular mass 

 (if it be still mixed with hgematin) or as a milky coagulum which 

 never becomes clear on filtration, and from which neither small 

 quantities of acetic acid or ammonia separate flakes capable of 

 being removed by filtration ; it is only when neutral alkaline 

 salts are added, and the solution is then boiled, that the fluid 

 becomes perfectly clear and flakes and small clots are depo- 

 sited. The following reaction is very characteristic of globulin ; 

 its solution is not precipitated either by acetic acid or by ammonia, 

 but it becomes strongly turbid when the fluid treated with acetic 

 acid is neutralised with ammonia, or conversely when after the 

 addition of ammonia it is neutralised with acetic acid. Its behaviour 

 simply with acetic acid is, however, also different from that of 

 albumen. On the addition of a little dilute acetic acid, the solu- 

 tion of globulin becomes opalescent, and when heated to 50 a 

 milky coagulum separates ; the fluid rendered turbid by a little 

 acetic acid, becomes clearer when more of the acid is added, but 

 always remains opalescent; this fluid does not coagulate till 

 heated to 98 ; it is only when a very great excess of acetic acid 

 has been added that the globulin ceases to be coagulable by heat. 

 The behaviour of globulin towards mineral acids and metallic salts 

 is precisely the same as that of albumen. It is also coagulated by 

 creosote ; it decomposes and becomes putrid much more readily than 

 the other protein-compounds ; when boiled it developes ammonia. 



Lecanu regarded this body as identical with albumen, Simon 

 with casein; we would rather place it by the side of vitellin, if the 

 elementary analyses were not opposed to this view ; but it appears 

 to us by no means advantageous to science, to group together 

 several ill-defined substances merely on the strength of a few 

 reactions, and without any definite proof of their similarity. 



Berzelius ascribes to the globulin, united in the blood with 

 hsematin, the singular property of dissolving in water containing 

 albumen and little or no salts, but not in water which holds in 

 solution large quantities of alkaline salts. He was in error in re- 

 garding the sediment of the blood-corpuscles which he named hsema- 

 toglobulin, as a simple mixture of globulin and hsematin ; for 

 we shall shew, in the second volume (in the section on " the blood"), 

 that this hsematoglobulin is composed of blood-corpuscles which 

 by the law of endosmosis become so distended in pure water as 

 scarcely to be visible under the microscope, but which (unless the 

 blood-corpuscles have burst from too great an addition of water) 

 again become apparent when we add a salt to the fluid in which 



