A STUDY OF TOAD POISON. 177 



considerable time. After from one to two months the phrynolysin 

 gradually becomes inert. Owing to the extreme lability of the toxin 

 there can, for the present, be no thought of obtaining the substance 

 pure, for even drying at room temperature weakens the poison con- 

 siderably. Owing to lack of material, a pharmacological examination 

 of the poison could not be undertaken. 



BEHAVIOR OF THE PHRYNOLYSIN TOWARD DIFFERENT SPECIES OF 



BLOOD. 



The method of testing was such that a series of test-tubes was 

 prepared, each containing 1 cc. of the dilution 1:10, 1:20, etc., i.e., 

 decreasing amounts of the poison. The dilutions were made with 

 0.85% salt solution. To each tube 1 cc. of the 5% blood suspension 

 in 0.85% salt solution was added. Thereupon the tubes were kept 

 at 37 C. for two hours and in the refrigerator overnight. A " com- 

 plete solution " is one that on shaking shows no body elements of 

 any kind: "almost complete " if there is still a slight sediment; and 

 " incomplete " when numerous blood-cells are undissolved. This is 

 followed in order by "red," "top," "trace," "O." 



Commencing with Table III all the experiments are made on sheep 

 blood. 



As can be seen from Table I, sheep blood is most strongly dis- 

 solved, frog and toad blood not at all. The limits of solution for 

 sheep blood are a dilution of 1:10240 in the case of phrynolysins 

 I and II, and 1:5120 in phrynolysin III. In Table IV, decreasing 

 amounts of the poison are added to 1 cc. 5% sheep blood. Of phry- 

 nolysin I, 0.0025 cc. sufficed to effect complete solution; of II and 

 III, 0.00025 cc. sufficed, and of IV, 0.005 cc. By determining the 

 amount of dry residue in poison solution II it is seen that 0.0000022 

 g. of organic substance suffice to completely dissolve 1 cc. 5% sheep 

 blood. Of poison solution III, 0.0000015 g. have the same effect. 

 If we assume that one-tenth of this organic substance (probably 

 it is still less) represents true phrynolysin, the rest being merely 

 indifferent albuminous bodies, we find that 3 /io mg. are sufficient 

 to completely dissolve one liter of sheep blood. 



The yield of phrynolysin is subject to individual fluctuations. 

 Animals freshly caught yield a stronger hsemolysin than those which 

 have been kept in captivity for some time. 



