THE CIRCULATING LIQUIDS OF THE BODY 27 



It becomes transparent or ' laky ' when by any means the pig- 

 ment is brought out of the corpuscles and goes into true solution. 

 Repeated freezing and thawing of the blood, the addition of 

 water, the passage of electrical currents, constant and induced,* 

 putrefaction, heating the blood to 60 C., and many chemical 

 agents (as bile-salts, ether, saponin), cause this change. Certain 

 complex poisons of animal origin, such as snake-venoms, bee- 

 poison, spider - poison or arachnolysin, and certain toxins pro- 

 duced by pathogenic bacteria for instance, tetanolysin, formed 

 by the tetanus bacillus also possess decided haemolytic power. 

 The blood-serum of certain animals acts on the coloured corpuscles 

 of others, and sets free their pigment for example, the serum 

 of the dog or ox causes haemolysis of rabbit's corpuscles ; the 

 serum of the ox, goat, dog, or rabbit lakes guinea-pig's corpuscles. 

 But rabbit's serum does not lake dog's corpuscles, and guinea- 

 pig's serum is inactive towards the corpuscles both of the rabbit 

 and the dog. It has been shown that in haemolysis by foreign 

 serum two bodies are concerned : one, which is easily destroyed 

 by heating to about 56 C., the so-called complement, and another, 

 the intermediary body or amboceptor, which is not affected by being 

 heated to this temperature. Thus, if dog's serum be heated to 

 56 C. for twenty minutes, no amount of it will lake rabbit's washed 

 corpuscles that is, rabbit's corpuscles freed from their own serum 

 by repeated washing with salt solution and centrifugalization. If, 

 however, serum which is not itself haemolytic for rabbit's blood 

 (e.g. , rabbit's or guinea-pig's serum) be added to the washed rabbit's 

 corpuscles, they will be laked by the heated dog's serum. Unheated 

 dog's serum will lake rabbit's corpuscles, whether they have been 

 washed free from their own serum or not (Practical Exercises, p. 63) . 

 The hypothesis which best explains these facts and many 

 similar ones is that dog's serum contains both of the* bodies 

 necessary for haemolysis of rabbit's corpuscles. When the 

 complement has been rendered inactive by heating, the ambo- 

 ceptor cannot cause laking by itself. Rabbit's serum contains 

 complement, but not the specific amboceptor necessary for the 

 laking of rabbit's corpuscles. Accordingly, the addition of fresh 

 rabbit's serum to heated dog's serum restores complement to 

 the latter, and thus it is again rendered active for rabbit's cor- 

 puscles. The amboceptor is supposed to unite on the one 

 hand with certain groups in the corpuscle and on the other with 

 the complement, which is thus enabled to develop its haemolytic 

 action upon the envelope or the stroma. The complement is 



* The laking action of induced currents is due simply to the heating of 

 the blood. Condenser discharges, which cause liberation of the haemo- 

 globin without raising the temperature of the blood as a whole to the point 

 at which heat-laking occurs, possibly act in the same way by causing local 

 heating of the corpuscles owing to their high resistance. 



