SECTION III. 



THE CYTOTOXINS OF BLOOD SERUM. 



The discovery of the cytotoxins dates back to the time when 

 blood-transfusion was first practised, it being noticed that the bloods 

 of different animals transfused into man were more or less directly 

 injurious, and not capable of replacing human blood for this purpose. 

 The transfusion of foreign blood led to the formation of clots, thrombi, 

 serous exudation, and more or less haemolysis. A resume of the 

 earlier work on this subject will be found in Ziemssen's Klinische 

 Vortrdge, 1887, wherein the observations of Panum, Ponfick, Hayem, 

 Landois and others are recorded. 



Especially important for our subject are the investigations of 

 Landois (1875) on blood-transfusion. He found that the transfusion 

 of foreign blood might prove fatal to an animal. The transfusion was 

 followed by haemoglobinuria due to the haemoglobin derived from the 

 injected blood corpuscles, but in addition to the dissolution of the 

 treated animal's corpuscles. Where the blood transfused emanated 

 from a closely related species Landois observed no ill effects to follow 

 its transfusion, this being the case for instance when transfusion was 

 practised between the dog and wolf, horse and donkey, hare and rabbit. 

 He concluded that large transfusions could only be practised between 

 closely allied species. The iirst to study the phenomena of haemolysis 

 in heterologous blood serum was Creite (1869), whose description of the 

 appearances observed leaves little to be desired. 



The term cytotoxin has been proposed by Metchnikoff (vi. 1900, 

 p. 369) for such animal poisons as affect cellular elements, whether they 

 be animal or vegetable. For the cytotoxins which dissolve the blood 

 cells the term haemolysin has gained general usage, and for this reason 

 I have retained the term in the following pages. Bordet (v. 1900, p. 

 257) prefers the term iiaemotoxin to haemolysin, but I see no 



