ODOR 107 



of the eye a little jet of blood upon their disturber. 

 Members of the U. S. Biological Survey, and others, 

 have experimented with this curious habit, and have 

 found the fluid to be real blood, and that the jet can 

 be repeated from either eye. 



It is hard to see the object of this, unless the 

 creature hopes to make the foe feel that it has 

 wounded him — perhaps by one of the spines — and 

 that he would better withdraw. Since the blood of 

 some animals injected into that of others is poison- 

 ous, it may be that it hopes to hit some place where 

 the skin is broken and thus poison its enemy. But 

 it is more probable that it is merely intended to 

 frighten. It is well known that grasshoppers and 

 other insects exude a harmless fluid when caught, and 

 that some caterpillars and beetles eject a very hurtful 

 acid at a disturber. It is well established that some 

 poisonous serpents can eject their venom many feet ; 

 but this seems to be the result of their attempt to 

 bite at the enemy, whereby the fluid is squeezed out 

 of the hollow fangs. The same muscle that closes the 

 jaws compresses the poison sac. 



Odor 



The Beptiles are, as a class, very bountifully sup- 

 plied with glands for secreting and pores for emitting 

 odorous fluids — not, however, for projecting to great 

 distances as in the skunks. AVhile some of these 

 odors are for defense, most are likely for charmino^ or 

 being agreeable, just as the beau or belle of to-day 

 uses the musk of an animal fur the same purpose. 



