Nature has endowed mammals with a more highly developed brain, while at the same time “withholding” chemical aids from them. It is difficult to find an acceptable explanation for this fact, but it is evident that a more highly developed nervous system is more easily combined with strong teeth, sharp claws, powerful muscles, and swift feet than with venom glands. However, there is one known mammal that can be counted among the venomous animals: the platypus (Fig. 1). It possesses a hollow venom spur on its hind legs, which is connected to venom glands. This spur is used to inflict injuries on a predator and inject venom into its body. The venom is not lethal to humans, but it is to small animals. Chemically, the venom of the platypus is little studied. Physiological studies have shown that it affects blood coagulation. It causes clots that can block important blood vessels.