26 
ON THE REPUTED 
from a consideration of Fayrer's experiments upon poisonous 
snakes. He has conclusively shown that a colubrine snake is 
"immune " from the poison of a colubrine snake and a viperine 
from that of a viperine snake, and as it seems probable that 
the poison of scorpions owes its activity to the presence of one 
of the same class of bodies — ptomaines — as the snake poison 
does, one might naturally expect to find that a scorpion 
was immune from its own poison and one scorpion from 
that of another ; this, as I have stated above, experiment 
has shown to be the case. 
The arrangement of the poison glands in a scorpion has 
never been described in detail. Some years ago I made out 
this arrangement in Etiscorpiiis italicus, but have not hitherto 
published my observations.^ 
The poison gland is double, and each gland is invested 
by a powerful muscle, the contraction of which expels the 
poisonous secretion. 
' E. Ray Lankester, Jourti. ItMuan Soc, Vol. XYI, p. ib' , footnote. 
