20 SEA-SHORE LIFE 
after a few trials it is invariably rejected. The tentacles on the 
other side of the animal will, however, conduct the paper to 
the mouth even after those on the side first experimented upon 
no longer accept it, and it is evident that the experience of one side 
of the animal has no effect upon the other side. 
It seems reasonable to assume that if an animal can be trained 
or can learn by experience it has associative memory, and therefore 
must be conscious, but it is certain that sponges, jellyfishes and 
worms have no trace of associative memory. 
On the other hand Robert Yerkes has shown that the green 
crab can learn to travel by the shortest path through a labyrinth to 
its food. 
It is also believed that the squids and octopi, which are the 
highest mollusks, have associative memory. 
However, practically all of the instincts of marine inverte- 
brates are inherited, and the behavior of the animal is not altered 
by personal experience or association with its fellows. They re-act 
to external stimuli with almost machine-like regularity, and we 
can generally predict what effect a ray of light, a current of elec- 
tricity, the attraction of gravity or a change of temperature will 
have upon the behavior of the animal. 
Essentially the same statements may be made concerning the 
re-actions of our own heart, lungs and digestive organs, and there 
is no more reason for the assumption that the lower marine animals 
are conscious, than that these organs of ours are conscious. The 
instincts of most marine animals are inborn and are inherited from 
generation to generation, whereas in higher forms some of the 
instincts are acquired by personal experience, and are not present 
at birth or necessarily predestined to appear during life. 
Interesting studies of this subject are given by C. Lloyd 
Morgan in “Animal Intelligence,’ London, 1896; and by Jacques 
Loeb, in ‘“‘Comparative Physiology of the Brain and Comparative 
Psychology,” 1902. 
It has been proved that each and every animal and plant be- 
gins life asa single cell, and that the body of the individual is 
built up asa result of the division and consequent multiplication 
of this cell. Indeed, in one great group, the Protozoa the entire 
animal consists of but a single cell, which performs all of the life- 
