The Life-History and Anatomy of Butterflies 
and a volume might be prepared upon this subject. It will, how¬ 
ever, suffice for us to call the attention of the student to the prin¬ 
cipal facts. 
The muscular system finds its principal development in the 
thorax, which bears the organs of locomotion. The digestive sys- 
' • - a) • ~ 
tern consists of the proboscis, 
which has already been de¬ 
scribed, the gullet, or oesoph¬ 
agus, and the stomach, over 
which is a large, bladder-like 
vessel called the food-reser¬ 
voir, a sort of crop preceding 
the true stomach, which is a 
cylindrical tube; the intestine 
is a slender tube, varying in 
shape in different genera, di¬ 
vided into the small intestine, 
the colon, and the rectum. 
Butterflies breathe through 
spiracles, little oval openings 
on the sides of the segments 
of the body, branching from 
which inwardly are the tra¬ 
cheae, or bronchial tubes. 
The heart, which is located in 
the same relative position as 
the spine in vertebrate ani¬ 
mals, is a tubular structure. 
The nervous system lies on 
the lower or ventral side of 
the body, its position being 
exactly the reverse of that 
which is found in the higher 
animals. It consists of nerv¬ 
ous cords and ganglia, or 
nerve-knots, in the different 
segments. Those in the head 
are more largely developed than elsewhere, forming a rudimen¬ 
tary brain, the larger portion of which consists of two enor¬ 
mous optic nerves. The student who is desirous of informing 
22 
