VENOMS IN THE ANIMAL SERIES 287 



plates, and motor and sensory nerves are spared ; the nervous 

 centres alone are attacked, especially the encephalon. The animal 

 dies without convulsions. 



Sea and fresh-water fishes (golden carp) are very sensitive to 

 this venom ; warm-blooded animals are refractory. It is therefore 

 probable that, in the species of Murex, the purple gland is a poison- 

 gland serving for defence, or for the capture of the prey upon which 

 these molluscs feed. 



Among the Cephalopods, the Octopods {Octopus vulgaris, 

 common octopus, Eledone moschata, musky octopus, of the 

 Mediterranean) possess two pairs of salivary glands, a small 

 anterior paii;, and a posterior pair of considerable size. 



The Decapods (cuttle-fishes [Sepia], &c.), have only posterior 

 salivary glands, of smaller dimensions in proportion to the size of 

 the body. 



On being crashed and macerated in water, the anterior glands 

 yield a limpid and slightly acid juice ; the posterior glands produce 

 a viscid, ropy fluid, filterable with difficulty and neutral. The 

 latter has an immediate paralysing effect upon Crustacea. It 

 contains a substance of a diastasic nature, precipitable by alcohol, 

 and destructible by heating for an hour at 58' C. 



Owing to the poisonous properties of this juice, Octopods 

 succeed in overpowering large prey, such as lobsters and crabs. 

 Once they are seized by the tentacles of the octopus, or cuttle-fish, 

 a bite inoculates these animals with venom that immediately 

 destroys their power of movement, and the Cephalopod is able to 

 contmue its meal in perfect security,' without having to fear the 

 pincers of its prey. 



An experimental study of this venom has been made by A. Briot,^ 

 who found that crabs are very sensitive to it, while rats, frogs, 

 rabbits, and fish do not appear to experience any inconvenience. 



^ Comptes rendus de la Societe de Biologie, February 25, 1905. 



