Studies on the Venoms of North American Pit Vipers

Summary This study of the venoms of North American pit vipers brings out the following points: The amount of venom secreted by each species varies directly with the size of the species.There are great differences in the toxicity of venoms from closely related species.The more primitive forms have venoms more toxic to the nerve centers.Species secreting a small amount of venom tend to have more active venoms, while those yielding large amounts have weaker venoms, so that the number of fatal doses in one extraction is more constant than are other factors.The larger species of viper give the largest number of fatal doses per extraction.The danger to man from the bites of pit vipers, varies almost directly with the size of the species.