410 C. O. WHITMAN. 
to such stimuli, whenever it occurred, appeared to be made 
at random rather than with a definite aim. Several times I 
held the finger just in front and a little to one side of the 
head; but the Leech swam on without turning to grasp it, even 
when held so near that the margin of the body grazed it in 
passing. 
2. Thirty to forty of these Leeches were captured and placed 
in a glass basin, and left until they had become quiet. Then 
the end of the finger was quietly rubbed over a small area on 
the bottom of the basin, care being taken not to arouse the 
Leeches by any sudden movement of the water. After with- 
drawing the finger, the basin was moved just enough to set 
the Leeches in motion. They began at once to search about, 
some swimming, others creeping, or stretching at full length 
and swinging from point to point. Ifthe expanded lip chanced 
to rest for a moment on the spot which had been rubbed with 
the finger, the Leech instantly showed unmistakable evidence 
that it tasted or smelled something agreeable, and began to 
examine the place with that quick and excited movement of 
the head which it shows when brought into direct contact with 
the finger. This behaviour must, I believe, be attributed to a 
sense of taste rather than smell, since it is not called forth 
except by actual contact with the lip. In the course of a few 
minutes several Leeches found the spot, and felt it over with as 
much delight as if it had been the finger itself. 
3. A drop of fresh blood was allowed to flow from a pipette 
over the dorsal surface of a Leech while in a state of repose. 
The Leech kept up a gentle undulating movement of the body, 
and gave no evidence of recognition. As soon, however, as the 
blood flowed over the margin of the lip the Leech became aware 
of its presence. 
This experiment, repeated many times, appears to me to 
show that the eyes and segmental sense-organs of Macrobdella 
do not function as organs of taste or smell. 
