118 THE MEANING OF EVOLUTION 
the attempt to capture anything which must be so 
ignominiously allowed to escape. If one’s clothing is 
well saturated with it, it is nearly useless to hope to 
remove the odor. A dog will carry the smell for sev- 
eral weeks. For a long time it will be so strong as 
to make him an unfit denizen of the house. Even 
swimming in deep water does not remove it. After 
two weeks, although he may seem to be practically 
free from the odor, a light rain will bring it all out 
again and make him nearly as offensive as before. 
Not as prompt in its action, but in the end nearly 
as effective, is the protective device which the toad 
sometimes uses to his distinct advantage. May I 
be pardoned a personal account of this particular 
feature. It was my good fortune to be for a short 
time a student in a class taught by Edward Drinker 
Cope, one of the most brilliant of our American bi- 
ologists. Prof. Cope mentioned in class the fact that 
the Batrachians (the group to which the toad be- 
longs) have in many cases the power to emit from 
their skin a fluid which is sufficiently nauseous to de- 
ter an animal from eating the creature that secretes 
it. Upon such authority as this, I had no hesitancy 
whatever in repeating Cope’s statement. One morn- 
ing I had a class in the field studying the ground ivy, 
whose dainty blue flowers were lifting themselves out 
of the dewy grass. While we were thus engaged, a 
