334 AN AMERICAN TEXT-BOOK OF PHYSIOLOGY. 



the bile acids, of the serum of other animals, by an excess of water, by 

 alternately freezing and thawing, and by a number of other methods. In 

 connection with two of these methods of discharging haemoglobin from the 

 corpuscles there have come into use in current medical and physiological 

 literature two technical terms which it may be well to attempt to define. 



Globuliddal Action of Serum. It was shown first by Landois that the 

 serum of one animal may have the property of destroying the red corpuscles 

 in the blood of another animal, thus making the blood laky. This fact, which 

 has since been investigated more fully, is now designated under the term of 

 " globulicidal " action of the serum. It has been found that different kinds of 

 serum show different degrees of globulicidal activity, and that white as well as 

 red corpuscles may be destroyed. Dog's serum or human serum is strongly 

 globulicidal to rabbit's blood. It would seem that this action is not due to 

 mere variations in the amounts of inorganic salts in the different kinds of 

 serum, since the remarkable fact has been discovered that heating serum to 

 55 or 60 C. for a few minutes destroys its globulicidal action, although such 

 treatment causes no coagulation of the proteids nor any visible change in the 

 liquid. This globulicidal action seems to be associated with a similar destruc- 

 tive effect of serum on bacteria its so-called " bactericidal action " but a 

 satisfactory explanation of either phenomenon has not yet been given. The 

 subject is complicated by the fact that the serum of some animals fails to give 

 the globulicidal reaction ; horse's serum, for instance, does not destroy the red 

 corpuscles of rabbit's blood. A discussion of the theories and facts bearing 

 upon the matter would lead too far into pathological literature, to which the 

 reader is referred for further information. 



Isotonic Solutions. When blood or defibrinated blood is diluted with 

 water, a point is soon reached at which haemoglobin begins to pass out of the 

 corpuscles into the plasma or the serum, and the blood begins to become laky ; 

 to obtain this effect different quantities of water may be required for the 

 b^ood of different animals, frog's blood, for example, requiring more water than 

 mammalian blood. It appears that the liquid surrounding the corpuscles must 

 have a certain concentration as regards salts or other soluble substances, such 

 as sugar, in order to prevent the entrance of water into the substance of the 

 corpuscle. There exists normally in the red corpuscle a certain quantity 

 of water, determined by the nature of its own substance and the attraction for 

 water exercised by the soluble substances in the liquid surrounding the corpus- 

 cle. If the concentration of the outside liquid is diminished, this equilibrium 

 is destroyed and water passes into the corpuscle ; if the dilution has been suf- 

 ficient, enough water passes into the corpuscle to make it swell and eventually 

 to force out the haemoglobin. Liquids containing inorganic salts, or other sol- 

 uble substances with an attraction for water, in quantities sufficient to prevent 

 the imbibition of water by the corpuscles are said to be " isotonic to the cor- 

 puscles." Red corpuscles suspended in such liquids do not change in shape nor 

 lose their haemoglobin. When solutions of different substances are compared 

 from this standpoint, it is found that the concentration necessary varies with 



