VENOMS OF THE TOAD AND SALAMANDER. 403 



diminution in the; numl^er of l:)lood corpuscles, rapid aboli- 

 tion of muscular contractility with paralysis, sensation h(jw- 

 ever persisting. 



By daily injections of increasin^r doses of salamandrine, 

 commencing with a non-lethal one, an animal can be rendered 

 immune so that it is unaffected by an amount which would 

 prove fatal to an untreated animal. For example, Phisalix 

 (18) gave a young dog weighing 2 kilograms subcutaneous 

 injections increasing from a -^ of a milligram up to 4 milli- 

 grams during a month without producing any ill effect. A 

 control animal weighing 2^ kilograms was then injected 

 with 4 milligrams and died at the end of twenty-four hours 

 with the characteristic symptoms. 



Another fact of interest is that with both the toad and 

 salamander the venom is fatal to the animal which secretes 

 it only in comparatively large amounts. Thus the last- 

 named author found the lethal dose of salamandrine for the 

 salamander to be from 5 to 10 milligrams subcutaneously^ 

 that is a dose from 50 to a 100 times greater than suffices 

 to destroy a mouse. Vulpian (9) made a similar observa- 

 tion with reoard to the toad and ascertained that the venom 

 of each of the various species is toxic to the remaining 

 species, though all have a general similarity in action — for 

 instance salamandrine is fatal to toads and tritons in 

 ordinary doses, the venom of the toad is fatal to tritons and 

 vke versa, while the venoms of the toad and triton poison 

 the salamander (21). 



The secretory apparatus of the venom glands is governed 

 by a nervous mechanism, the centres for which are located 

 in the optic lobes as was shown by Phisalix and Contejean 

 (22). Muscarine, strychnine and ammonia excite secretion, 

 while cocaine, eserine, and morphine inhibit it. It was inci- 

 dentally noticed that the salamander is remarkably refractory 

 to certain poisons, it is only completely curarised by 43 milli- 

 grams of curare while morphine is apparently quite inactive. 

 The interesting fact was demonstrated that the salamander's 

 blood and blood-serum act as an " antitoxin " towards curare 

 (23). The following experiments illustrate this — 20 parts 

 of the defibrinated blood were mixed with \\ parts of a i 



