88 Chapter IV 



[94] Ehrlich and Morgenroth 1 , in a series of memoirs on the solution of 

 red blood corpuscles, have combated the idea that there is only a single 

 alexine in one and the same serum. Moreover, they state that alexine 

 always requires for its action the aid of another substance, and that 

 matters are much more complicated than at first sight appears. They 

 maintain that in each normal serum a number of different substances 

 are found, each one of which only attacks a single species of red blood 

 corpuscle. They point out that the solution of the red corpuscles by 

 the normal serum takes place through the combined action of two 

 different substances and cite several cases where a normal serum, after 

 being heated to 55 C. and so deprived of its haemolytic power, again 

 becomes capable of dissolving the red corpuscles when some normal 

 serum from another species, which of itself is destitute of the solvent 

 property, is added to it. Let us quote an example from Ehrlich 

 and Morgenroth. The normal serum of the goat readily dissolves 

 the red blood corpuscles of the rabbit and guinea-pig, but if heated 

 for half an hour at 55 C., it loses this power. On the other hand, 

 the normal serum of many horses shows itself powerless to dissolve 

 the red corpuscles of these rodents. Here, then, are two serums, 

 equally incapable of effecting the solution of the red corpuscles of the 

 rabbit and guinea-pig. Yet, when they are mixed together and to 

 them a few drops of blood from one of the rodents cited is added, 

 haemolysis takes place readily. The heated goat's serum then, has, 

 retained in it something that resists a temperature of 55C., a sub- 

 stance which, by itself, leaves the red blood corpuscles intact : but 

 which, when combined with a second substance present in the horse's 

 serum, causes their solution. Ehrlich gives to the first substance, 

 that is to say that found in the heated goat's serum, the name of 

 intermediary body (" Zwischenkorper "). The second substance, pre- 

 sent in the unheated horse's serum, is designated by him the comple- 

 ment. In order that a normal serum may dissolve the red corpuscles, 

 it is not sufficient that it should possess a single substance, the alexine 

 of Buchner. It must, to exert this action, contain two distinct sub- 

 stances which are very often found together in the same normal serum. 

 Unheated goat's serum was only capable of dissolving the red blood 

 corpuscles of the rabbit because a particular complement and 

 intermediary substance were both present. Deprived of its comple- 

 ment at 55 C., the serum is solvent only when we add to it another 



[95] substance that is contained in the normal serum of a different species 

 1 Berl kiln. Wchnschr., 1899, SS. 6 and 481. 



