1885.| Affinities of Annelids to Vertebrates. 767 
mal body by the channel of the sense organs and the sensory 
nerves. Reaching a ganglion it is received by the cells, perhaps 
by many of them through the division of the fiber into its con- 
stituent fibrille. It either continues over its original fibrille to 
the motor nerves which issue from these cells, or is transferred, 
partly or wholly, to other fibrillæ by induction. In sucha case 
it may be carried to other motor nerves, or enter upon a short 
local circuit and yield the local effect called memory ; that is, a 
peculiar organizing effect in which is represented its peculiar 
character. Or this secondary circuit may convey it toa higher 
or more central ganglion, in which the same modes of distribu- 
tion may be exercised. In highly developed animals it may pass 
through several such intermediate ganglia, and be finally, in part 
or wholly, transferred by induction to the cerebral ganglion. In 
this it exerts but one action, that whose effects we call memory, 
a permanent transformation produced, in some organizable sub- 
stance. This effect is the germ of all mental development. 
(To be continued.) 
:0:— 
AFFINITIES OF ANNELIDS TO VERTEBRATES. 
` BY E. A. ANDREWS. 
LS a group the annelids exhibit in a prominent degree both 
bilateral symmetry and segmentation. The former is well 
expressed in the adult, in the early larval stages and even at the 
period of closure of the blastopore, when the radial symmetry of 
the gastrula becomes replaced by bilateral symmetry. 
Segmentation, so pronounced in the adult, is not found in what 
we may regard as the most primitive larval form, the Trochoph- 
ora of such forms as Serpula, or as more perfectly expressed in 
some species of Polygordius. 
These two fundamental characters, bilateral symmetry and seg- 
mentation, naturally lead to a comparison of this group with the 
other segmented Bilateralia, of which the Vertebrata especially 
have attracted attention in seeking for the allies of the annelids , 
or rather in the attempt to derive the vertebrates from inverte- 
brate groups, the annelids have furnished important ai 
Of those who have paid especial attention to the subject and 
who maintain a close relationship between the annelids and verte- 
brates, may be mentioned Semper, Dohrn and Hatschek. Sem- 
per seems to have advanced the most evidence in support of his 
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