268 
DEVELOPMENT OF BEES 
modified in accordance with the function 
which they are to assume. 
The egg of the honeybee is shaped 
somewhat like a banana and is about 6-100 
of an inch long. One end is slightly larger 
than the other, the egg adhering to the bot¬ 
tom of the cell by the smaller end. The 
embryo is always formed on the longer or 
convex side of the egg, its lower or ventral 
surface directed outward, the head at the 
larger end. The egg is in appearance pearly 
white, and slightly translucent. It is cov¬ 
ered externally by a very thin but tough 
membrane whose surface is covered by a 
delicate network of ridges. The egg of the 
bee contains a relatively large quantity of 
yolk, the protoplasm being comparatively 
small in amount. On this account cell 
division is restricted to the interior of the 
egg, the cells thus formed later rising to 
its surface to form a layer from which all 
the parts of the future larva are formed. 
The first conspicuous evidence of the 
future embryo is the appearance, during 
the second half of the second day, of a 
bandlike thickening on the long side of the 
egg (Fig. 2). On this thickening, at the 
larger end of the egg the appendages begin 
a lai'va. Flnt, fore intestine; Hint, hind intestine; 
Mint, mid intestine; VNC, ventral nerve cord. 
to appear as rounded protuberances, the 
antennae (Ant) and the mouth parts (man¬ 
dibles and maxillae, Md. lMx, 2 Mx) being 
the first to appear. Behind them are the 
rudiments of the three pairs of legs (L 1, 
L 2, L 3). At about the same time the 
rudiments of the stigmata and tracheal sys¬ 
tem appear as a single row of pits on each 
side (Sp). The rudiments of the silk or 
spinning glands (Slk G) also appear as 
pits just behind the second maxillae. On 
the upper or dorsal side of the head are 
also seen two pairs of swellings (Br) which 
constitute the rudiments of the brain. At 
Fig. 4.—Four stages in the development of the 
honeybee: a, egg; b, young larva; c, old larva; d, 
pupa. 
this stage, therefore, nearly all of the im¬ 
portant organs of the larva are outlined. 
The changes leading to the completed larva 
are illustrated by Figs. 2c and 2d. In Fig. 
2c a number of important changes are seen 
to have taken place. The bandlike embryo 
has widened, growing toward the dorsal 
or concave side of the egg. The mouth 
(Mth) and anus (An) appear as deep pits 
at the two opposite ends of the embryo. 
They join with cell masses on the interior 
to form the alimentary canal, the parts 
forming the fore and hind intestines, the 
cell masses the mid intestine (Fig. 3, Mint). 
The mouth parts have changed little, but 
the upper lip (Lm) is now represented by 
a flap-like growth. The Malpighian tu¬ 
bules, MT, the excretory organs of the 
larva, have arisen as outgrowths of the 
hind intestine. The pits constituting the 
tracheal invaginations have enlarged to 
form sacs, and each of these in turn sends 
out three hollow outgrowths, one of which 
extends forward and one backward, to 
meet those of the neighboring segments, 
and one extends downward to join the cor¬ 
responding branch in the same segment on 
the opposite side (Fig. 2, Tr). The pit-like 
rudiments of the silk-glands (Slk-Gl) have 
