The venom of _Heterometrus maurus_ is, however, toxic enough to the sparrow. When one of these little birds is inoculated in the pectoral muscles with the contents of the poison-glands of a single scorpion belonging to this species, the following symptoms are observed: Immediate rigidity, doubtless connected with the pain, then, after a few seconds, depression and relaxation of the muscles. The bird remains upright, but its body sinks down more and more until it comes into contact with the ground; if on a perch, it soon becomes unsteady and drops off. There is dyspnœa, which any effort increases, and death supervenes suddenly; all at once the sparrow falls on its side, stiffens, sometimes has a few convulsions, and then finally becomes still. The time occupied by these phenomena is always short, although it varies from two minutes to half an hour. Scorpion-venom is a strong irritant to the mucous membranes. When dropped into the eye of a rabbit it produces acute ophthalmia. It has often been asserted that scorpions kill themselves with their own venom if enclosed in a circle of fire. This is an absolute myth, for it is easy to prove by experiment, as was done by Bourne at Madras,[120] that these animals cannot be intoxicated by their own poisonous secretion, nor by that of other individuals of the same species. Moreover, it has been established by Metchnikoff,[121] in very definite fashion, that the blood of the scorpion is antitoxic. If 0·1 c.c. of this blood be added to a dose of venom lethal to mice in half an hour, a mouse injected with this mixture resists indefinitely. This antitoxic power is exhibited both by _Scorpio afer_ and the Algerian _Androctonus_. (c) =Myriopods.= It has been shown by Phisalix and Bertrand that certain species of Myriopods, including those of the genus _Julus_ (Order _Chilognatha_, _e.g._, _Julus terrestris_), secrete throughout the entire extent of their body a volatile venom, which these authors compared to _quinone_. The species of the genus _Scolopendra_ (Order _Chilopoda_; _Scolopendra cingulata_, found in the South of France, Spain and Italy; _S. gigantea_ and other forms, common in Africa, India, Indo-China and Equatorial America), have the second pair of post maxillary appendages transformed into formidable poison-claws, with which they can inflict bites which are very painful to human beings. [Illustration: FIG. 98.--_Scolopendra morsitans_ (S. Europe). (After Claus.)] The tropical species may attain a length of 10 or even 15 cm. Their bodies are composed of 21 segments, each provided with a pair of jointed legs. They live in shady places, such as woods, hidden under stones, dead leaves, or the bark of old trees. They feed upon small insects, spiders, and larvæ, which they kill with their venom. The latter is secreted by a racemose gland situated at the base of the poison-claws; it escapes by a duct which opens at the apex.