June 21, 1924 
Morphology of the Honeybee Larva 
1203 
of the rudiments are inclined at an angle of about 45 degrees to the median plane 
(PL 8, G, Ov .). The ventral half of each rudiment is traversed at right angles to 
its long axis by a large number of slender parallel columns or strings of cells with 
deeply stained cytoplasm, each column consisting of several rows of such cells 
(PL 8, H). These columns are assumed to be the rudiments of the ovarian tubules 
of the imaginal ovary. Their ventral ends extend to the ventral borders of the 
ovarian rudiments; the spaces between them are filled with branched connective 
tissue cells. 
Along the ventral margin of each ovarian rudiment is a groove, at the bottom 
of which is located a ridge (Pl. 8, H, Ovd) composed of minute vacuolated cells. 
The base of this ridge is closely associated with the ventral or distal ends of the 
ovarian tubules. Near the posterior end of the rudiment the ridge becomes 
separated off as a solid cord of cells, taking a ventrad and caudad direction (Pl. 8, 
I and K, OvD ), evidently becoming the rudiment of the oviduct. 
Numerous tracheoles are found within the connective-tissue matrix surround¬ 
ing the ovarian tubules. In some cases end cells have been observed within the 
rudiments of the ovaries. 
In a mature larva, reared in a queen cell, the rudiments of the ovaries are long 
reniform structures (PL 8, L, Ov ). measuring about 2.25 mm. in length and attached 
to the ventral wall of the heart in the 5th abdominal segment. The anterior 
ends of these rudiments, which lie on the boundary between the 4th and 5th 
abdominal segments, are each prolonged to form slender pointed processes like 
those found in the worker larva. With the exception of these insignificant pro¬ 
cesses the entire ovarian rudiment of the queen larva is composed of transverse 
parallel columns of dark-staining cells, assumed to represent the future ovarian 
tubules, similar to those of the worker larva but far more numerous, of larger 
diameter, and extending from the ventral to the dorsal margin. These are of 
course united by a connective tissue network. The (presumptive) rudiments of 
the oviducts are similar to those of the worker larva. 
TESTES 
These are relatively enormous structures, measuring about 3.75 mm. in length 
and 1.25 mm. in breadth, and lie on either side of the heart in the 4th, 5th and 
6th abdominal segments, close to the dorsal body wall. They are elongate 
reniform in outline (Pl. 8, J, Tes) and somewhat compressed in a dorso-ventral 
direction. Like the ovarian rudiments, those of the testes are made up of 
numerous parallel transverse cell strands bound together by connective tissue. 
The (presumptive) rudiments of the vasa diferentia ( VDef) are similar to those 
of the oviducts in the worker and queen larvae, but more delicate and more 
difficult to demonstrate. 
TECHNIQUE 
Several fixing fluids were tried for killing and fixing bee larvae, but none gave 
as general satisfaction as Carnoy’s acetic-alcohol mixtures. Their success is 
largely due to their superior power of penetration, since the chitinous cuticle of 
the larva, although very thin and delicate, is almost impenetrable by aqueous 
solutions. 
The study of the internal organs by dissection is made difficult by the short 
and curved form of the larva, its small size, the abundance of fat cells and the 
general delicacy of the tissues. The preparation represented by Plate 4, A, 
was made from a larva fixed in Carnoy’s fluid, stained over night in Mayer’s 
carmalum and heavily destained (4 to 6 hours) in acidulated alcohol. The body 
wall, muscles, coagulated blood, etc., were then removed bit by bit with a needle, 
the stain rendering possible the identification of the different organs and tissues. 
