434 HJEMOLYSINS AND ALLIED BODIES 



their being no longer capable of retaining haemoglobin, the latter 

 leaving the corpuscles to become dissolved in the serum. This 

 laking of the blood can be easily observed in a test-tube as 

 the normally opaque suspension of corpuscles changes to a 

 transparent solution. By this means, then, we are furnished with 

 a ready method for studying the laws which govern, and the 

 conditions which influence, the production of anti-bodies towards 

 foreign cells in general. 



. It will, of course, be impossible, in this lecture, to deal with the 

 general question of immunity in all its aspects ; all that can be at- 

 tempted is to discuss briefly the laws which govern the production 

 and action of anti-bodies in general, taking haemolysis as a type ; and 

 to indicate, here and there, by way of example, some of the more 

 important applications of these laws to Physiology and Pathology. 



On thoroughly understanding the process of haemolysis, no 

 difficulty will be experienced in understanding such processes a& 

 those of bacteriolysis (destruction of bacteria), cytolysis (destruc- 

 tion of cells), agglutination, and praecipitin formation. In 

 studying the process of haemolysis we will incidentally find it 

 advantageous to consider antitoxin formation. 



Hcemolysis. A red blood - corpuscle is composed of an 

 envelope or membrane filled with haemoglobin. 1 The envelope 

 (and stroma) consists chemically of three substances : the phos- 

 phorised fat lecithin, the mon-atomic alcohol cholesterin, and 

 a nucleo-proteid ; and it prevents the haemoglobin from leaving 

 the red blood-corpuscles and becoming dissolved in the blood 

 plasma. This envelope is possessed of a certain amount of 

 vitality, for if it be killed, it can no longer prevent the 

 diffusion of haemoglobin into the surrounding fluids, so that 

 laking of the blood results. Any protoplasmic poison will kill 

 the envelope and cause haemolysis, because the osmotic pressures 

 of serum and corpuscular contents are not quite the same, that 

 of the serum being a little less than that of the corpuscular 

 contents. Physiologists have for long recognised this as the cause 

 of the haemolysis, which is produced by the repeated freezing and 

 thawing of the blood, or by the addition to it of certain chemical 

 poisons. Other poisons, e.g. sapotoxin, seem to damage the 

 envelope by uniting with the cholesterin and possibly with the 



1 Some workers think that there is also a stroma or sponge- work in the interior 

 of the corpuscle.^) 



