Cellular Immurdty, 



83 



to arrest the rat's heart as is required bo arrest the rabbit's heart in the same 

 time. 



The conclusion was drawn that the congenital tolerance of the rat to 

 strophanthus is due chiefly, if not entirely, to an insusceptibility of the 

 heart of this animal to the action of strophanthus. This poison was par- 

 ticularly suitable for establishing such a quantitative relationship — if it 

 existed — as arrest of the hfeart is the primary cause of death in strophanthus 

 poisoning. 



Two subsidiary points were established which find a parallel in the 

 experiments to be described in this paper. In the first place, the ratio 

 of 30 : 1 — the concentration necessary to arrest the rat and rabbit heart 

 respectively — held good only for such lower concentrations as arrest the 

 heart slowly ; with high concentrations, the ratio was nearer 2 : 1. The 

 theoretical bearing of these results is discussed in the original paper. In the 

 second place, though the rat's heart showed a specific insusceptibility as 

 compared with the rabbit's heart to the action of strophanthus, comparable 

 to the difference in the lethality of strophanthus for the intact animals, no 

 diffdrence was found between rat's and rabbit's red blood corpuscles in their 

 resistance to strophanthus haemolysis. 



Many years ago, Kanthack (9) made a careful quantitative study of the 

 relationship between the lethality and haemolytic action of cobra venom for a 

 variety of cold- and warm-blooded animals, and came to the conclusion that 

 " there is no absolute relation between the haemolytic reaction of the blood 

 of an animal to cobra poison and the resistance of the animal itself to the 

 poison." 



"We have in these papers a series of observations, made, with different 

 poisons, to determine whether any relationship exists between cellular 

 resistance and natural immunity. From its convenience and familiarity 

 as an experimental cell, it was natural that the red blood corpuscle should 

 be eijiployed in cases where the poison acted on it. It is however 

 important to realise that, alike with eel-serum, cobra venom, and stro- 

 phanthus, no consistent relation, if any, was found to exist between natural 

 immunity of the animal and resistance of its erythrocyte to haemolysis. On 

 the other hand, in the case of strophanthus, when the heart was employed, 

 the existence of a quantitative relation between immunity of the animal and 

 resistance of the heart was clearly demonstrable. The significance of this, 

 especially the failure of the red cell as a reliable index of cellular immunity, 

 will be discussed later. 



(b) Acquired Immunity. — It is of perhaps greater interest to determine 

 whether, when an animal is actively immunised to a toxin, the cells of the 



