652 THE AMERICAN NATURALIST. [Vor. XXXIX. 
will make them jerk violently away if it touches them in any 
place while mixing with the water. . A drop of strong ammonia 
does the same. The ammonia throws down a precipitate of 
ammonium chloride on the surface of the water, and if this 
drifts against them before dissolving they show extreme irrita- 
bility. Inallthese cases it is largely the sense of touch that is 
affected, as the reaction was the same whether the mixing drop 
touched the tip of the tentacle, the rim of the nose, or the side 
of the head, and it was the touching of the mixture that pro- 
duced the effect, except in the case of the alcohol, for it was 
found that when the visible mixture of the drop of acid or am- 
monia stopped even an eighth of an inch away from. the fish, 
there was no reaction. With the ammonia this could be seen 
still more plainly, for wherever the ammonia was dropped, it was 
not until the ammonium chloride touched the skin, whether on 
tentacle, tip of nose tube, or skin at the side of the head, that 
the jerking away occurred. With the alcohol it was sometimes 
a drop that touched that caused the effect, sometimes not. 
With the many drops put in, only some of which touched the 
hag, and those not affecting it, it may be that the sense of smell 
was excited, or it may be that the alcohol finally irritated the 
mucous membrane lining the nasal tube, or possibly the skin of 
the tentacles. The foregoing experiments with the acid and 
ammonia were begun at half-past three o'clock, and were contin- 
ued until five. By that time the eels had become very languid 
and were lying in the crescent shape. The next morning they 
were all right again. 
Notwithstanding the negative results of these experiments in 
regard to the sense of smell, there is no question but that it is a 
most serviceable sense for the hagfish. As they cannot see, it 
is the means by which they know when they are near food. I 
cannot tell at what distance they can detect an object by the 
sense of smell. When the dead fish was placed in the tank, as 
stated above, and the hagfish within six inches were aware of it 
immediately, it took a perceptible time for those farther off to 
become so, but the scent reached those as far off as eighteen 
inches to two feet. How much farther it would go I do not 
know. It probably varies with different individuals. 
