102 INSTINCT 
instincts of the animal are by no means monopolized by the 
brain, but that the various ganglia of the ventral nerve cord 
are the controlling centers of many activities. If we cut 
the commissures connecting the brain with the chain of 
ventral ganglia, the reactions of the eyes and antennz take 
place in the usual way. If the eye stalk is stimulated it is 
withdrawn; if the antennules or antenne are touched they 
are drawn back, but there is no reaction from the legs. On 
the other hand, if a leg is seized an effort is made to with- 
draw it; if this is not successful other legs may be employed 
to push against one’s hand or the chelipeds may reach over 
and pinch the offender. The crayfish can walk in the usual 
manner, and when placed in the water it can swim as well 
as a normal individual. Its movements are more restless 
than before, owing to the lack of inhibitory impulses which 
under ordinary circumstances are issued from the brain. 
Food is seized by the chelipeds, passed to the mouth parts, 
chewed and swallowed; if stones or other innutritious objects 
are presented to the mouth parts they are at once rejected, 
showing that connection with the brain is by no means 
necessary for the proper discrimination of food. 
If the commissures are cut farther back, between the sub- 
esophageal and the first thoracic ganglia, power of moving 
the legs still remains, although locomotion is somewhat 
impeded. If a leg is seized it is withdrawn or defended by 
the other appendages. Pieces of meat or paper given to the 
chelipeds are passed from one to the other and pressed 
between the mouth parts where they may be seized and 
swallowed. Often the mouth parts are tardy in responding, 
and the chelipeds may vainly persist for hours in pressing 
the object against them. Sometimes bits of food are torn 
to pieces and then offered to the mouth parts. Stones or 
other hard objects are not passed to the mouth, and if seized 
