52 The Philippine Journal of Science me 



placing a tight clamp on the rubber tubing connected with the 

 free end of the tracheal cannula and by connecting the rubber 

 tube with short pieces of glass tubing whose diameters at one 

 end had been flamed to about 0.9 and 1.5 millimeters, respectively. 

 Apomorphine hydrochloride (0.1 cubic centimeter of a 2 per 

 cent solution per kilogram of body weight) was injected intra- 

 muscularly at varying intervals from the commencement of 

 respiratory obstruction. When the occlusion was complete, or 

 when the animals were made to breathe through a circular 

 opening of about 0.9 millimeter in diameter, the vomiting center 

 became quickly paralyzed and apomorphine failed to cause vomit- 

 ing, even if it was injected at the same time that the respiratory 

 obstruction was accomplished. However, when the animals were 

 made to breathe through a larger opening of approximately 1.5 

 millimeters in diameter, the vomiting center remained irritable 

 to apomorphine. This observation was not continued longer 

 than two hours, but judging from the behavior of the animals at 

 the end of the observation, the vomiting center would probably 

 have remained irritable even after hours of this degree of 

 asphyxiation. These results are illustrated in the subjoined 

 protocols : 



Protocol 1. November 5, 1915. Male dog, 12.05 kilograms. 



10.25 a. m. The dog was put under light ether anaesthesia, the tracheal 



cannula inserted, the wound closed, and the anaesthesia 



discontinued. 

 2.55:30 p.m. The dog had recovered from the anaesthesia. A clamp was 



placed tightly on the rubber tube connected with the 



tracheal cannula. 

 2.55:60 p.m. Apomorphine hydrochloride (0.1 cubic centimeter of a 2 per 



cent solution per kilogram) was injected intramuscularly 



in the gluteal region. 

 2.56 p. m. Retching occurred, and the dog fell to the floor. 



3.00 p. m. The heartbeat was not palpable. 



Protocol 5. December 21, 1915. Female dog, 5.27 kilograms. 



11.45 a. m. The tracheal cannula was inserted, the wound sewed, and 

 etherization discontinued. 



2.02 p. m. The tracheal cannula was connected to a glass tube with 



an opening of about 0.9 millimeter in diameter. Apomor- 

 phine hydrochloride (0.1 cubic centimeter of a 2 per cent 

 solution per kilogram) was injected intramuscularly. 



2.04:30 p.m. Retching occurred, and the dog fell to the floor. 



2.08 p.m. The dog was unconscious, the muscles were relaxed, and the 



limbs dropped limp when lifted. The femoral pulse was 

 hardly perceptible. 



