122 THE VENOM OF HELODERMA. 



contractions had almost ceased calcium and potassimn chlorides were added. 

 In others, the venom was dissolved in Ringer's solution and the strips trans- 

 ferred to this at the same period. In some of the experiments the strips were 

 alloAved to remain in the venom solution until they ceased to contract; in 

 others they were left in the venom only part of the time. These differences 

 may be seen by referring to the protocols. The amount of venom varied in 

 the different experiments between 0.1 and 0.01 per cent. 



In order to determine the effect of possible inorganic substances, some 

 tests were made with a solution of the ash from incinerated venom. This was 

 found to have no influence on the heart. Certain lots of venom were heated to 

 80° C. for an hour and then kept at 37° C. for 3 days. This heating did not 

 seem to influence the activity. The "heated venom" of the protocols was 

 prepared in this way. 



The extreme toxicity shown by sample B (see protocols 7 to 10) was evi- 

 dently due to some artificial contamination, possibly from the saliva or mouth, 

 and not to the venom itself, as the effect of this venom when injected was not 

 different from that of the others. 



PROTOCOLS. 



(1) Venom A. — Heart of small painted turtle (Chrysemys picta) removed 

 and the ventricle cut into five pieces, equal in size. Each strip placed, at 3 

 p. m., in normal salt solution containing venom as follows : No. 1, 0.07 per cent; 

 No. 2, 0.035 per cent; No. 3, 0.015 per cent; No. 4, 0.005 per cent; No. 5, con- 

 trol. All began irregular contractions which soon ceased. At 5 p. m. all were 

 beating; at 5^ 30" Nos. 1 and 2 ceased; at 7 p. m. No. 4 ceased; at 9 p.m. Nos. 3 

 and 5 stopped. 



(2) Venom A .■ — Heart of shghtly larger painted turtle, treated as before. 

 The auricle in one piece was used as an additional control. Amounts of venom 

 as in 1. Heart removed at 3 p. m. At 6 p. m. Nos. 1, 2, and 3 had ceased to 

 beat. Added 1 to 10,000 calcium chloride to each, which immediately started 

 contractions. At 6'' 30" No. 1 contracted every 28 seconds; No. 2 every 120 

 seconds; No.3 every 12 seconds; No.4 everylS seconds; No.5 every 25 seconds; 

 No. 5o every 6 seconds. At S"" 30" No. 1 and No. 2 have ceased entirely; No. 3 

 almost entirely; Nos. 4, 5, and 5a still beat strongly. At 9'' 30" No. 5a stopped; 

 at 6 a. m. No. 4 stopped, and soon after No. 5 stopped. 



(3) Venom A. — Heart of painted turtle. Ventricle cut into four strips; 

 auricle used as No. 2. Placed at 3 p. m. in salt solution containing venom as 

 follows: No. 1, 0.1 per cent; No. 2, 0.05 per cent; No. 3, 0.025 per cent; No. 4, 

 ash of 0.05 per cent; No. 5, control. At 5 p. m. all beating feebly; add to each 

 0.03 per cent CaClj and 0.01 per cent KCl. All begin contractions. At 6 

 p. m. all still beating, but more feebly. Add 0.01 per cent CaCU, contractions 

 increase. At 10*" 30" all have ceased. Transfer to plain 0.85 per cent NaCl 

 solution; only No. 5 beats. At ll"" 30" transfer to Ringer's solution without 

 venom for the night. The following day at 10 a. m. transfer to plain 0.85 per 

 cent NaCl solution and 5 minutes later to venom; Nos. 1 and 3 contract. No. 

 1 ceasing soonest. 



(4) Venom A. — Heart of painted turtle. Ventricle cut in four strips, 

 auricle set as No. 2. Removed at 3 p. m. and placed in salt solution contain- 

 ing venom as follows: No. 1, 0.08 per cent; No. 2, 0.04 per cent; No. 3, 0.02 per 



