STRUCTURES IMPLICATED IN METAMORPHOSIS. 
13 
and the body ends in a tubercle. Their consistence is the same 
throughout, and the constituent membrane is almost homoge- 
neous. The third, fourth, fifth, sixth, and the ninth segments of 
the abdomen have a pair of tubercles furnished with spines on 
their underneath or ventral surface. These tubercles, which are 
destined to disappear when the insect passes into the chrysalis 
LARVA, OR CATERPILLAR. ADULT FORM, OR MOTH. 
The same insect, Attacus pavonia major , in the larval and adult stage, seen from 
underneath. 
condition, act as legs. They are not true legs, but only prolon- 
gations of the skin ; but they are used as holders and locomotive 
organs, and under the term of membranous feet or legs are 
invariably present in caterpillars. 
Now compare the abdomen of the moth with that of the 
caterpillar. 
The number of the segments is no longer the same, and only 
seven can be counted. The first has joined itself to the chest-piece 
