9 8 
ANIMAL ACTIVITIES. 
tiny thread. They moult often, and very soon, with¬ 
out any teaching, they know how to spin their tiny 
wheel-shaped webs. They eat other insects, as do 
their elders, and often dine on one another. For them 
the struggle for existence is a fierce one, and domestic 
relations count for little, the mother eating not only 
her own children, but often making a meal of her 
husband. In the spider family the mother is supreme 
and husbands and children fare but ill. 
Discovery. An examination shows how large is 
the nerve-mass concealed in the cephalothorax of the 
spider. Several ganglia have grown together and 
produced a sort of second brain, considerably larger 
than the nerve-mass which lies above the throat. 
Not only is this brain large, but as it is made by the 
concentration of many smaller nerve-masses, or gan¬ 
glia, it represents a great concentration of power. 
These nerve-masses are connected with the outside of 
the spider’s body everywhere by nerves, which carry 
to the central organs notice of all vibrations from with¬ 
out. The spider then is extremely sensitive to any 
change in its surroundings. It sees, though not very 
clearly, by means of eight eyes placed on the front part 
of the cephalothorax; it hears, if at all, by the vibration 
of the hairs on its body. It tastes and smells, we have 
no doubt; but its keenest sense is that of touch. 
Movements. The spider is capable of few move¬ 
ments and performs these exceedingly well. What 
she loses by the absence of wings she gains by increase 
of power and skill in the use of her legs. The making 
of a web often requires the most delicate movement 
and the greatest precision; and the spider shows this 
delicacy and precision to perfection. The wonderful 
thing about the spider’s automatic movements is the 
accuracy with which they are controlled. 
The Lithobius. For purpose of comparison a little 
time may be devoted to the many-legged brown insects 
which disappear so hurriedly when one overturns a 
