June 21, 1924 
Morphology of the Honeybee Larva 
1187 
posterior ends of which frequently project far into the anterior end of the mid¬ 
intestine (Pl. 5, C, Ctl). 
The external surface of the mid-intestine, as already stated, is covered by a 
delicate network of muscle fibers. A small portion of this sheet, stripped off 
from the mid-intestine, is shown in Plate 5, D. The central or inner surface is 
uppermost. The inner layer ( LMcl ) is composed of branched muscle cells whose 
delicate processes, connecting adjacent cells and thus forming an anastomising 
plexus, tend to run in a longitudinal direction. Below these, and morphologi¬ 
cally outside of them, is a layer of transverse muscle fibers ( TMcl ). These are 
closely and uniformly spaced, and are also quite uniform in caliber. The nuclei 
of the cells composing this layer are much smaller than those of the inner layer. 
The muscle cells of the transverse layer are also interconnected by extremely 
delicate protoplasmic processes, some of which are indicated in the figure. 
The hind-intestine (PI. 4, A, Hint) is a cylindrical tube of fairly uniform 
diameter except at its anterior end, where it shows a funnel-like or bell-shaped 
expansion, the larger end of which is applied to the posterior end of the mid¬ 
intestine. From this point it bends ventrad, taking a cephalad course to the 
sixth abdominal segment, where it bends sharply upon itself and takes a direct 
course caudad to its termination on the tenth abdominal segment. The hind- 
intestine of the honeybee larva exhibits a simpler structure than that of the ant 
larva, in which the posterior portion of the hind-intestine is enlarged, narrowing 
again near the anus, three divisions being thus formed, small intestine, large in¬ 
testine and rectum (35). This condition also exists in the larva of the beetle 
Anobium (23). 
As already stated, the anterior end of the hind-intestine exhibits a funnel¬ 
like or bell-like enlargement (PI. 4, A). The end of the funnel is, however, not 
open, but is closed by an extremely thin layer of minute cells (PI. 6, A, dph), 
which is continuous around the margin of the funnel with the epithelial wall of the 
mid-intestine. This epithelium, on the sides of the funnel-like enlarged portion, 
is thick and composed of a large number of slender club-shaped cells (PI. 6, A, 
Hint). These give place, at the neck of the funnel, to larger prismatic or co¬ 
lumnar cells. The remainder of the epithelium of the hind-intestine is formed of 
cells of this type. This is thrown into deep folds, as shown in Plate 5, E, pro¬ 
jecting almost to the center of the lumen and giving the latter a stellate aspect in 
section. Relatively stout muscle fibers (TMcl) encircle the hind-intestine, 
being found from the margin of the funnel-like expansion to the anus. These 
are for the most part arranged in a single layer, but toward the posterior end they 
become more numerous and are arranged in two or even three layers. Outside 
of the transverse muscles are a few irregularly arranged longitudinal fibers (PI. 5, 
E, LMcl). In the 10th segment numerous slender muscle fibers run between 
the lateral hypodermis and the lateral walls of the hind-intestine. 
The posterior termination of the hind-intestine, the anus, is a simple trans¬ 
verse slit situated on a slight elevation in the center of the 10th abdominal 
segment. 
The mode of attachment of the mid- and hind-intestines in the larvae of the 
aculeate Hymenoptera is of special interest and has been studied and described 
in detail by Rengel ( 44 ) in the wasp (Vespa), in the ant (Lasius) and in the 
honeybee. With the exception of minor details, it is the same in the three groups. 
As shown in Plate 6, A, at the extreme posterior end or fundus of the mid-intestine 
there is an outpushing (st) of the epithelium, thus forming a rounded projection 
on the external surface of the fundus. In Vespa this projection is quite prominent, 
forming the “ stalk ’* (Stiel) of Rengel. In the honeybee larva it is externally 
merely a low rounded eminence; internally it is represented by a depression of the 
epithelium, the bottom of which is formed by a heap of irregular transparent cells, 
