104 INSTINCT 
ceans is the peculiar trait shown by several species of spider 
crabs of decking themselves out with a covering of seaweed, 
sponges, hydroids, etc., so that they are quite effectually 
concealed in their natural surroundings. Spider crabs 
kept in aquaria have been seen by several observers to snip 
off bits of seaweed with their pincers, reach over their backs 
and stick them down among the stiff curved hairs which 
occur on the upper surface of the carapace. The seaweeds 
and sessile animals thus transplanted often grow, so that 
the back of the crab comes to be a veritable botanical and 
zoological garden on a small scale. There are few instinc- 
tive acts which appear to be more the result of deliberate 
intention, yet the disguisement is not only instinctive, but, 
as Minkiewicz has shown, it is performed by crabs in which 
the brain is entirely cut off from connection with the legs by 
cutting the esophageal commissures that lead to the large 
ventral ganglion. The sense of wonder with which instinct 
was formerly regarded, and which the reflex theory might 
seem to rudely destroy, is a sentiment which can scarcely 
fail to arise when we contemplate the organization which 
makes possible the blind performance of such remarkable acts. 
Among the insects, as in the Crustacea, the seat of many 
instincts is in the ventral ganglia rather than in the brain, 
A decapitated fly is able to walk and fly and go through with 
elaborate movements of cleaning the wings, legs and body. 
In experiments made by the writer on the water scorpion, 
Ranatra, it was found that after decapitation the insects 
were able to walk and swim almost as well as before. In 
fact, they became much more restless and would walk about 
for hours without coming to rest; and when they finally 
became quiet they could be aroused by the slightest stimuli. 
When placed on their backs they would readily right them- 
selves. If the tip of the breathing tube was seized while the 
