Cellular Immunity. 



87 



acquire it. But the experiments to be described, I think, render the red cell& 

 still further suspect as a test of cellular immunity. The peculiar character 

 of the red cell has not been sufficiently realized and, it may be, has been the 

 means of preventing work on cellular immunity, for though it is the test 

 object that would first suggest itself, it is the most misleading guide to the 

 condition of the cells generally. 



In 1912, as a preparation for the scheme of experiment now undertaken, I 

 investigated in greater detail than had hitherto been done the action of cobra, 

 venom on isolated mammalian tissues. I came to the conclusion (21) that 

 cobra venom contains some substance having an action closely approximating 

 to a sympathomimetic action. Cushny and Yagi later (22), working with a 

 different sample of venom, obtained results differing in certain particulars, 

 especially in the fact that they obtained no inhibitory action on smooth 

 muscle and no stimulation of secreting glands such as I had obtained ; and 

 they therefore came to the conclusion that cobra venom does not contain any 

 substance of sympathomimetic action. In regard to a difference of results of 

 this nature, it is well to keep in mind that snake venoms are, so far as 

 is known, substances of complex nature and presumed to contain a variety of 

 toxins of varying stability. Complete concordance of results in regard to 

 primary action cannot, therefore, be expected with different samples of venom- 

 collected in different ways, and kept under different conditions and for 

 different times. It is, however, interesting to find that Abel and Macht (23) 

 have discovered in the skin secretion of the toad two substances (a) a 

 substance having an action like digitalis, and (h) adrenaline. Cushny and 

 Yagi found that cobra venom acted rather like digitaUs, while I found that 

 it acted rather like adrenaline. Perhaps the question as to whether both may 

 not occur in cobra venom, as in toad poison, ought to be left open. The 

 question ought to be decided by determining the action of a perfectly fresh 

 venom and by examining the glands for the chromaphil reaction. In any 

 case the venom I have now used resembles more nearly that employed by 

 Cushny and Yagi. Especially, this sample of venom caused a marked rise of 

 tone in the isolated rabbit's intestine ; but the addition of a minute trace of 

 adrenaline (1 in 30,000,000) prevented this rise of tone even with high 

 concentrations of venom and produced an effect exactly resembling that 

 previously found by me. 



