VENOMS IN THE ANIMAL SEBIES 273 



by contact with the anemones, they should be advised to cover 

 their bodies with a layer of grease, a simple artifice which con- 

 stitutes an efficient protection. 



B . — ECHINODERMS. 



The Echinoidea (Sea-urchins) are provided with soft prehensile 

 organs, the pedicellarim, of which four kinds are distinguished : 

 gernmiform, tridactyle, trifoliate, and ophiocephalous. 



These pedicellariss contain a' special venom, which causes the 

 paralysis and death of animals into which it is injected. Uexkull, 

 who was the first to mention it, considered that the gemmiform 

 pedicellarise alone are toxic. 



From this point of view various species of sea-urchins, Strongy- 

 locentrotus lividus, Arbacia csquituherculata, Sphcerechiniis granu- 

 laris and Spatangus purpureus, have recently been studied by 

 V. Henri and Mdlle. Kayalof.' 



The pedicellarise were removed and pounded up in sea-water, 

 and the pulp was injected into crabs, holothurians, star-fish, cuttle- 

 fish, frogs, lizards, and rabbits ; in the case of cuttle-fish and rabbits 

 the injection was made intravenously ; in that of the other animals 

 into the body-cavity. 



For crabs the lethal dose was from 20 to 30 gemmiform pedi- 

 cellarise of Strongylocentrotus lividus. 



The holothurians, star-fish, and frogs proved immune. 



In the case of rabbits weighing 1^ kilogrammes, 40 pedicellarise 

 of Spharechinus granulans, pounded up in 1 c.c. of water, produce 

 death by asphyxia and general paralysis in from two to three 

 minutes. The heart continues to beat after respiration has ceased. 



For lizards and fishes the toxic dose is the same as for the crab. 

 The cuttle-fish is paralysed and killed in two hours by 50 

 pedicellarise. 



' Comptes rendus de la Societe de Biologie, May 19, 1906. 

 18 



