The Life-History and Anatomy of Butterflies 
and the fluids in the cup of the flower flow up the proboscis and 
into the bulb. The bulb is also surrounded by muscles, which, 
when contracting, compress it. The external opening of the 
tube has a flap, or valve, which, when the bulb is compressed, 
cl. 
Fig. 32. —Interior view of head of milkweed butter¬ 
fly : cl, clypeus; cor, cornea of the eye; cc, oesophagus, or 
gullet;//;?, frontal muscle; dm, dorsal muscles; Im, lat¬ 
eral muscles; pm, muscles moving the palpus (Burgess). 
closes and causes the fluid in it to flow backward into the gullet 
and the stomach. The arrangement is mechanically not unlike 
that in a bulb-syringe used by physicians. The process of feeding 
in the case of the butterfly is a process of pump¬ 
ing honeyed water out of the flowers into the stomach. 
The length of the proboscis varies; at its base and on 
either side are placed what are known as the maxillary 
palpi, which are very small. The lower lip, or la¬ 
bium, which is also almost obsolete in the butterflies, 
has on either side two organs known as the labial 
_ palpi, which consist of three joints. In the butter- 
Labiai palpus flies the labial palpi are generally well developed, 
of Colias, though in some genera they are quite small. The 
magnified 10 , r , AjL . . . . A Al 
diameters. antennae of butterflies are always provided at the ex¬ 
tremity with a club-shaped enlargement, and because 
of this clubbed form of the antennae the entire group are known 
as the Rhopalocera, the word being compounded from the Greek 
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