UY C. J. MARTIX A\D FRANK TIDSWELL. 497 



feature of the curves shown. This may be due either to weakening- 

 of the heart's action or to diminished peripheral resistance caused 

 by a sudden paralysis of the whole vasomotor centres, or to both 

 causes combined. We are strongly of opinion that the former is 

 the principal cause, Ijut as the data at our disposal do not prove 

 this to be the case, it is useless to discuss it further. 



The drowsiness and general depression which formed so 

 prominent a feature in the recorded cases following wounds from 

 the spurs, and was also seen in our first experiment, would result 

 from this fall of blood j)ressure and the consequent diminution of 

 l)lood supply to the nervous system. As in these cases the poison 

 was injected under the skin, it would only reach the general 

 circulation slowly, and the onset of the symptoms would be more 

 gradual. 



Our first experiment also shows the local irritant action follow- 

 ing subcutaneous injection, which is marked l)y great oedema 

 and tenderness. 



The capillary hicmorrhages found in our other cases are another 

 manifestation of this ii'ritant action. 



Altogether there appears to lie a remarka])le analogy between 

 the venom of Australian snakes and the poison of the Platypus. 

 This resem])lance is indicated by the following tal)ular state- 

 ment : — 



(1) The poisons both owe their toxic properties to proteid 



constituents. 



(2) They both markedly retard or prevent the coagulation of 



the blood when small doses are slowly introduced. 



(3) They both cause intravascular clotting when injected 



intravenously in sufficient doses. 



(4) They both cause an almost instantaneous drop in the 



pressure of the blood. 



(5) They both cause capillary hiemorrhages and cedema when 



locally applied. 

 In the i^roduction of local redema plat}']^)us poison appears to be 

 much more powerful. Snake venom, on the other hand, is 



