INTRODUCTION. xlv 
We have frequently observed the young Talitrus escape 
from the mother, upon the capture of the latter; and 
from the active state of their existence at this time, they 
appear as if they had long been capable of so acting, if 
they had required it. The observation of Dr. Salter on 
the common Gammarus, detailed at page 380 of the first 
volume of this work, fully confirm this fact—as does the 
circumstance that the young of Arcturus are protected by 
the mother, who supports and carries them about on the 
antennee. Also we have been able to corroborate the 
observation of Mr. H. Goodsir, that the Caprella carries 
about its young attached to its body. These, together 
with the fact that many genera, particularly of the 
Podoceride, protect and nurse their young for some time 
within nests, which they build apparently for no other 
purpose, afford abundant proof that in these animals 
there is a conscious love of offspring that appears to 
be less marked in animals far higher in the scale of 
scientific classification. 
When the young of Gammarus first swims about as a 
free animal, it only resembles the parent in a modified 
degree. The antenne show no distinction between the 
peduncle and the flagellum. The latter is shorter, and 
consists of but five articuli, while thirty to forty may be 
present in the parent. This relative proportion is visible 
also in the lower antenne, and in the secondary appen- 
dage of the upper, which increases with advancing age, 
until the adult stage is acquired. 
In the structure of the eye we see the same gradual 
increase going on after the animal has become free. The 
lenses in the young are from ten to twelve in number, 
whereas, in the adult, from sixty to eighty may be counted. 
In many genera it also changes its colour, as does also 
that of the animal itself. 
