Abstract: A low effective dose of a biologically acceptable chemical sterilant is injected into the dorsal cranial portion of a scrotal testis of a male animal for the purpose effecting sterilization of the animal. The injection of the chemical sterilant into the dorsal cranial portion has an effect on the epithelium of the tubuli recti, rete testis and ductus efferentes in addition to stopping spermatogenesis in the seminiferous tubules.

Abstract: An instrument for measuring the size of a testis has a pair of relatively displaceable jaws with testis contacting surfaces. The spacing between the jaws is displayed on a scale calibrated to a recommenced dose of a chemical sterilant at a given concentration for the testis measured for sterilizing a male animal having scrotal testes. The instrument is used to determine the appropriate dose to be administered the animal, each testis of which should be independently measured as the size of the testicles may different in the same animal.

Abstract: A handheld electrocardiogram monitor with electrodes mounted on swing arms which are rotatably mounted on the bottom case of the ECG monitor housing, to which the swing arms are frictionally engaged and also engaged by means of a detent mechanism which includes a combination of detent grooves and ball spring plungers. The grooves are provided with 60.degree. spacing on standoffs mounted on the swing arm, and the ball plungers are mounted on the bottom case of the monitor in positions 90.degree. apart about the rotational axis. The 60.degree. phasing of the grooves combines with the 90.degree. spacing of the plungers to provide 30.degree. indexing.