Insect Life.” 287 
thing which is considered necessary to the constitution of an animal 
is so unequivocably present, that any one would be laughed at who 
should refuse to bestow that title on their possessor (an insect for 
instance), and yet by the familiar use of this word, animal, we are 
led to form conclusions unsupported by experience, and, starting 
with the belief that it implies a being that feels, we argue from 
the name to the fact, and from the fact back again to the name.” 
Next is the assertion, “ that insects do not feel.” ‘The power 
to feel appertains only to those creatures in whom the life of 
growth has reached its consummation. It is admitted on all hands 
that higher degrees of intelligence are associated with higher de- 
grees of anatomical structure, especially of the nervous system, 
and it is equally certain that the sensibility of creatures is in pro- 
portion to their intelligence : hence we should expect sensation to 
be more or less perfect according as the nervous system is more 
or less developed, and its amount to be immediately connected 
with all those physical conditions upon which intelligence has also 
been ascertained to depend, viz. the temperature and colour of the 
blood, the absence or presence of a spine, and the form and sub- 
stance of the brain. Accordingly, it ought to follow that the 
sensibility of creatures of cold blood, such as fish, amphibizee and 
reptiles, where few or no traces of intelligence can be discovered, 
should be proportionably low ; and in point of fact the signs of it 
are very faint and few. Surely, therefore, when we descend lower 
still, and come to creatures of the same kind as Anacreon’s Cicada, 
—creatures altogether without blood(!)—and this deficiency is 
common to all the insect tribes, —it is reasonable to expect that 
the sensibility of which we had observed the progressive decline 
in passing from the higher to the lower qualities of the circulating 
fluid, should here be totally obliterated.” 
A comparison of the nervous system of the different orders of 
animals is then made, showing that in the brain and spinal cord 
of the vertebrata ‘all that qualifies the animal to feel is cen- 
tralized, and from the same originating cord all that enables it to 
move proceeds to its destination.” In the class of insects, on the 
contrary, there is no brain; ‘a medullary cord runs through the 
whole body of the animal, giving branches to the different organs 
in its way. Placed at intervals upon this cord, something like 
beads, or lying between its two elementary threads, are seen 
roundish knobs, which have obtained the name of ganglia: they 
afe various in size, uncertain in number, and are placed at unequal 
distances in different tribes of insects; but in no case do they, as 
far as visible structure is concerned, present the least similarity to 
