THE EDUCABILITY OF A SNAIL 59 
haved. For what captured specimens very gener- 
ally do on the slightest provocation—even jarring 
the aquarium a little—is to expel the air from their 
breathing chamber, retract into their shell, and drop 
to the bottom, where they may sulk for an hour. 
Realizing that this nervousness would make ex- 
perimenting impossible, Miss Thompson began by 
“taming” her captives. They were taken in the 
hand at intervals and moved about under water; 
they were held till they protruded from the shell; 
they were abundantly handled, till they became so 
accustomed to it that they could be touched by the 
observer, or moved from one dish to another, with- 
out retracting their body or expelling the air from 
their lung. This “taming” is a further evidence of 
adaptability. 
Very interesting data as to the educability of 
animals have been obtained by using simple laby- 
rinths in which the creatures are placed at repeated 
intervals to see whether they learn to get out more 
quickly in the course of experience. It has been 
‘found useful in many cases to reward, say with 
food, a rapidly successful solution of the labyrinth, 
and to punish, say with a slight electric shock, the 
taking of the wrong road. Most of these experi- 
ments have been made with animals of high degree 
like cats and mice; Miss Thompson has spent much 
time and ingenuity in inquiring whether the laby- 
rinth experiment can be adjusted so as to apply to 
freshwater snails. In one form of the experiment 
a Y-shaped cylindrical glass tube was anchored 
