INTELLIGENCE IN LOWER VERTEBRATES 227 
a cerebral cortex, which is lacking in the bony fishes, cannot 
be said to surpass the latter in the development of intelli- 
gence. The tailed amphibians are notoriously sluggish and 
give every appearance of extreme stupidity. Nevertheless 
they show a remarkably acute and delicate sensibility and a 
power of very rapid action on occasions which is belied by 
their general appearance and customary slow movements. 
Our knowledge of their intelligence is slight. Few have 
attempted to educate such apparently unpromising subjects 
and neither Brehm, Biichner nor Romanes gives any re- 
markable cases illustrative of their sagacity. Professor 
Whitman, in his interesting account of the behavior of 
Necturus, considers that this animal has a certain amount of 
intelligence which is involved in its learning by experience 
how to direct its movements, but he assumes nothing be- 
yond this. Pieron has observed that if worms enclosed in 
a glass tube are introduced into an aquarium with specimens 
of Triton, the amphibians make a large number of attempts 
to seize the worms before showing any noticeable falling 
off in the number of their fruitless efforts; fish under similar 
circumstances learn to avoid the worms much more quickly. 
In another experiment a quadrangular flask containing 
several worms was placed on its side for a half hour a day 
in an aquarium, containing six tritons. Sometimes the 
animals found the entrance by chance and ate some of the 
worms. With the exception of one individual which seemed 
to learn the way fairly quickly there was no marked increase 
in the facility with which the tritons entered the flask. The 
experiment, while not thorough-going, indicates that asso- 
ciations in these animals are usually formed but slowly. 
Among the Anura there have been several studies on the 
intelligence of frogs and toads. These animals are capable 
of forming simple associations, but their powers are very 
