472 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1909. 
The animals thus operated upon become greatly excited, rmnning 
incessantly here and there, and fighting with all the other crabs they 
meet. But they disguise themselves at once, and in quite a normal 
manner without, however, any reference to the color of the sur- 
roundings. 
The fact of the persistence of normal concealment in blinded ani- 
mals is of very great importance, because it proves that the primor- 
dial cause of that instinct is not in the photoperceptions. It is 
rather the tangoperceptions, or the tactile receptions of the claws, 
and of the flexible dorsal hooks, which give rise to the whole series 
of instinctive actions previously described. If that is true, then in 
order to accomplish these operations the animals have no need of the 
action of their cerebral ganglia, all the movements of the buccal and 
thoracic extremities having their centers in the central ganglionic 
mass. 
V. THE INSTINCT OF MAJA AFTER THE COMPLETE SEVERANCE OF 
THE BRAIN. 
It is impossible for me to give here either a description of the 
method of operating or detailed observations on the animals operated 
upon. I shall simply point out that I made use exclusively of the 
sharp hook employed for the first time by Ward, and that I always 
performed the operations on the ventral side by Bethe’s method 
slightly modified. 
If the operation is well done® the animals, after the severing 
above the csophagus of the two longitudinal connectives, the only 
communication between the cerebral ganglia and the subcesophageal 
ganglionic mass, live long enough (I have kept them as long as five 
weeks) for one to study them sufficiently. 
When the shock of the operation has disappeared, all the most 
complete reflexes remain intact, as has been known for the last ten 
years from the excellent work of Bethe: The animal can walk, chooses 
its nourishment, eats well, defends itself, etc. 
But what interests us especially is, that it begins before long to 
clean itself, scratching the hooks with its claws, especially those of 
the ambulatory feet and the posterior extremity of the thorax, but 
also, though very rarely because of the weakness of the muscles, those 
of the superior surface of the thorax. If the crab happens to touch 
with its claws a piece of paper or alga, it is often seen to disguise 
itself, executing the whole series of movements without omitting 
any, and in the same order as when in the normal condition. 
@This is verified in studying the simple reflexes, especially those of the 
antenne and the eyes. After the observations are finished an autopsy is 
performed. 
