HEMOLYSIS AND BACTERIOLYSIS. 301 



Metchnikoif and Buchner regard the leukocytes as being the 

 source of the complements or alexins, the former considering them 

 as due to the breaking down of the corpuscles, the latter as true 

 secretory products. Other authorities regard the connection between 

 these complements and the leukocytes as not established. Wasser- 

 man believes the leukocytes to be one source, but not the only one, 

 while Ehrlich and Morgenroth claim that the production of the 

 complements is one of the functions of the liver. 



Hemagglutinins and Bacterial Agglutinins. The normal serum 

 of the goat possesses also the power of agglutinating the red cells 

 of the human being, the pigeon, and the rabbit i. e., causing them 

 to adhere, forming clumps. The normal serum of a rabbit will 

 agglutinate the bacilli of typhoid fever. This property is due to 

 substances in the serum called agglutinins ; those which agglutin- 

 ate the red cells being distinguished as hemagglutinins. It is 

 believed that there is a separate agglutinin for each species of 

 blood-cells. The hemolysins and the agglutinins are not identical 

 substances, for a serum can retain its agglutinating power after its 

 hemolytic power is lost. 



Cytotoxins. If an animal is injected with white blood-cells, 

 spermatozoa, etc., substances are produced in its serum which bring 

 about a dissolving action in the cells used for the injection. These 

 substances are termed cytotoxins. Thus, if the leukocytes of a rab- 

 bit are injected into a guinea-pig, the serum of the guinea-pig will 

 dissolve the leukocytes of a rabbit ; in this instance the cytotoxin 

 is called leukotoxin. The action of such serum is believed to be 

 due to interacting substances, as in the case of hemolysis. If sper- 

 matozoa are injected, a cytotoxin is produced, called spermatoxin. 



Precipitins. If, instead of injecting cells, the dissolved albu- 

 minous bodies of one species of animal are injected into another, 

 there is a precipitation of albumin. Thus, if a rabbit is injected 

 with the serum of a horse, and subsequently the rabbit serum is 

 mixed with that of a horse, the mixture becomes cloudy, owing to 

 the precipitation of the horse's albumin. The substances which 

 produce this precipitation are termed preoipitins. 



A practical application has been made of the knowledge 

 obtained by this research into the nature of precipitins in the 

 identification of blood-stains. For the details of the method the 

 reader is referred to text-books treating of the subject. Ewing 

 states that the reaction does not fail with very old specimens of 

 blood, although it becomes less distinct the older the specimen. 

 Ziemke obtained a cloudiness in three hours from a blood-stain 

 twenty-five years old ; from blood mixed with earth three years 

 old ; from decomposed blood ; and from human blood highly diluted 

 with six other kinds of blood. A solution of iron rust gave no 

 reaction. Uhlenmuth secured positive results with blood of a three 

 months 7 decomposed cadaver. Stern obtained the characteristic 

 reaction in solutions of 1 of serum to 50,000 of blood. Ewing 



