406 C. O. WHITMAN. 
make it any the less probable that the lateral-line organs are 
homologous with the segmental sense-organs of the Leech. 
In respect to the nerve supply of these organs, a modifica- 
tion of its segmental character has been brought about in the 
head of the Leech analogous to what is seen in the body of the 
Fish. As is now well known, the lateral-line organ of the head 
of the Fish are each supplied with a segmental nerve-branch, 
while those of the body are supplied with branches from a 
single lateral nerve. In the Leech the segmental sense- 
organs of the body are each supplied with a segmental nerve- 
branch, while in the head (cf. Leydig’s fig. 5, pl. 11) we find 
a single nerve sending branches to two or more segmental 
sense-organs, and the same nerve supplying one or more pairs 
of eyes and numerous goblet-shaped organs of the lip. In 
this latter particular we have a good illustration of the fact 
that nerves are not functionally differentiated according to 
the different sense-organs they supply. 
The facts here presented appear to warrant the opinion that 
at least three different functions are represented in the sense- 
organs of the Leech. The evident serial homology of the eyes 
with the segmental sense-organs, and the presence of large 
clear cells in both classes of organs, suggest that the different 
sense-organs may not be limited to the exercise of a single 
function. ‘This view has been put forward by Ranke on the 
ground that the different sense-organs have been derived from 
a common morphological basis. It must be admitted that 
they originally exercised one or more functions in common; 
and their structural differences, while indicating plainly that 
they have made some progress in the direction of specialisa- 
tion, are not so great as to exclude the possibility, or even the 
probability, that they are still able to do several kinds of work 
incommon. With Claus I regard the goblet-shaped organs of 
the lip as organs of taste; but it seems almost certain that 
they function also as tactile organs, as was maintained by 
Leydig. When blood is placed in contact with the lip of the 
Leech its behaviour plainly indicates that it has the power of 
taste. In creeping about the lip is protruded, and the margin, 
