1204 
Journal of Agricultural Research 
Vol. XXVIII, No. 12 
This method of dissection was the one usually employed. Fresh material was 
not found satisfactory. Very successful entire preparations of separate parts, 
such as the head, were made by staining for 18 to 24 hours in carmalum and 
afterwards destaining in acidulated alcohol (0.1 per cent) for about the same 
length of time. To demonstrate the dorsal diaphragm, the larva was first 
killed and the body wall and muscles fixed by immersion in absolute alcohol for 
five minutes. The dorsal body wall was then removed with the aid of fine 
scissors, spread out on a slide, ventral surface uppermost, and the fat body 
gently pushed away from either side of the dorsal mid-line, thus uncovering the 
dorsal diaphragm. The latter was then fixed with any convenient fixing fluid, 
stained rapidly (5 minutes) with Ehrlich's haematoxylin, dehydrated, cleared, 
and mounted, together with the dorsal body wall, to which it remains attached. 
Sections were made in the usual manner. Celloidin sections 30 to 40 microns 
thick were found very useful in determining the relation and size of organs. 
Sections of material imbedded in paraffin were cut 6 to 8 microns in thickness, 
since the completeness of the series was usually more important than extreme 
thinness of individual sections. Prior to embedding, the larvae \vere either cut 
in half, or, when sagittal sections were desired, an aperture of considerable size 
was made in the lateral body wall. Infiltration is complete in 4 to 6 hours, if 
xylol has been used for clearing. 
Iron haematoxylin proved to be the only satisfactory stain for sections of 
material embedded in paraffin, the other haematoxylin stains being too diffuse 
in their action. A counter stain such as Orange G or alcoholic solution of eosin 
is useful in differentiating certain structures, such as nerve fibers or the albu¬ 
minoid granules of the fat cells. Material intended for celloidin sections was 
stained in bulk with Mayer's carmalum. 
SUMMARY 
(1) The bee larva has a fusiform shape, the posterior end being the smaller, 
and is flexed ventrad. Its color is ivory white. The larva is divided by con¬ 
strictions into a head and 13 segments, 3 of which belong to the thorax, the 
remainder to the abdomen. The sternal surface of the abdomen is sharply 
demarcated from the lateral surfaces by the ventrolateral suture. The ventro¬ 
lateral region of abdominal segments 1 to 9 is raised to form a series of rounded 
swellings, the epipleural lobes. 
Ten pairs of spiracles are present, situated on the lateral faces of the 1st and 
2d thoracic and the first eight abdominal segments, near their anterior limits. 
The head is short and blunt and the neck constriction is a narrow fold. The 
labium is prominent, bluntly conical, slightly compressed dorso-ventrally, and 
bears on its tip the common opening of the silk glands. The maxillae and 
mandibles are papillate, the mandibles being more pointed than the maxillae 
and curved mesiad. A well-defined groove, the lateral furrow, runs from between 
the bases of the mandibles and maxillae caudad to the neck constriction. The 
labrum is broad and flat, slightly bilobed at its apex, and is indistinctly marked 
off from the clypeus. The labrum and labium are separated by a narrow cleft- 
like space, the mouth opening, which is bounded laterally by the mandibles and 
maxillae. On each side of the clypeus the antennal rudiments are evident as 
circular papillate elevations. 
(2) The body wall consists of a single epithelial layer of small cells, the hypo- 
dermis, clothed externally by a delicate cuticle. The hypodermis differs greatly 
in thickness in different parts of the body but its.average thickness is greatest in 
the head. The cuticle also is here thicker and more rigid than elsewhere. The 
antennal rudiments are ovoid in form and situated in deep peripodal cavities, 
