98 Messrs. J. A. Gunn and R. St. A. Heathcote. 



immunity, as if the type of efifect in the acquired immunity was approxi- 

 mating to that of congenital immunity. 



(c) Intestine. 



In order to get rid of effects due to the presence of antitoxin, it was 

 necessary to wash out the serum from the gut previously to trying the 

 action of the venom. For these experiments, therefore, the gut was washed 

 out in situ by perfusion with warm Locke's solution by means of a cannula 

 tied into the aorta, and connected with an elevated reservoir containing 

 the perfusing solution. This was done both in the case of the normal 

 and immunised animal, in order that the intestine should go through the 

 same manipulations in each case. Segments of the gut were afterwards 

 cut out and used for experiment in the ordinary way, and a large number 

 of experiments could in this case be done with the gut of one animal. Ifc 

 was found in the case of the intestine as in the case of the heart that 

 the muscle of the immunised animal, free from serum, was less sensitive 

 to the toxic action of the venom than that of the normal animal. In 

 figs. 7 and 8 is shown a comparison of the effect of 1 in 10,000 upon the 

 normal gut with that of 1 in 5,000 upon the gut of the immunised animal. 

 Though in the latter case the concentration was twice as great, the toxic 

 effect is conspicuously less. 



It follows from these experiments that, when an animal is immunised 

 to cobra venom, the tissues of the gut acquire an increased resistance to 

 the toxic action of the venom, apart from the protective action of the 

 antitoxin serum. 



(d) Red Blood Corpuscles. 



The method of experiment and technique were the same as in the 

 experiments previously described (p. 94). 



The venom solution was again divided and used for both experiments, 

 so that the corpuscles of the normal rabbit and of the immunised rabbit 

 were subjected to exactly the same concentration of venom. The corpuscles 

 were thrice washed, and the saline solution used was 0"85 per cent, sodium 

 chloride in distilled water. 



In 3| hours the following changes had taken place : — (a) Normal cor- 

 puscles. Complete haemolysis by venom in concentrations down to O'Ol per 

 cent., partial haemolysis with 0*005 per cent., and no haemolysis with less 

 concentrations. (6) Corpuscles of immunised animals. Complete haemolysis 

 by venom in concentrations down to 0'0033 per cent., partial haemolysis 

 with 0'002 per cent., and no haemolysis with less concentrations. 



In other words, the corpuscles of the immunised animal are more easily 



