June 21, 1924 
Morphology of the Honeybee Larva 
1201 
and projecting centrad into the body cavity (PL 5, A, 1-3F). In the arrange¬ 
ment of these masses a certain amount of bilateral symmetry exists. Carri&re 
and Burger (7), in their description of the larval mason bee, divide the fat body 
into three sections: (1) That part, situated dorsad to the lateral tracheal trunks 
and below the dorsal diaphragm (PL 5 A , IF); (2) that part situated ventrad to 
the lateral tracheal trunks ( 2F); (3) that part situated above the dorsal diaphragm 
and comprising one to three layers of cells ( 3F ). These divisions are only incom¬ 
pletely separated and are merely of topographic value, since there are no differ¬ 
ences in the morphological character of the cells themselves. As shown in 
Plate 5, A, the fat cells are most abundant peripherally, next to the body wall, a 
considerable space around the alimentary canal being left vacant (see p. 1184). 
In advanced larvae fat cells are abundantly present in contact with the hypo- 
dermis, but not attached to it, throughout the trunk, crowded between the hypo- 
dermis and muscles and also beneath the ventral nerve cord. A few fat cells 
are likewise present in the head, lying against the posterior surface of the brain 
and below the suboesophageal ganglion. The various open spaces in the fat 
4 body, constituting channels for the flow of blood, have been described in a previous 
section (see p. 1199). 
Bishop (4) has published a detailed account of the structure and development 
of the fat cells of the honeybee larva, to which the reader is referred for more 
extended information on this subject. In quite young larvae the deutoplasm of 
the fat cells (Pl. 8, D and E, F) is commonly found represented in each cell by 
a single relatively large vacuole (y), while the nucleus is still more or less spherical. 
In larvae three to four days old the deutoplasm of the fat cells (PL 8, F, y) is 
scattered throughout the cytoplasm in the form of vacuoles of various sizes; at 
the same time the nuclei begin to show distortion. Plate 8 illustrates a typical 
fat cell ( F) from a mature larva, in which the nucleus has assumed the shrunken 
and branching form characteristic of this stage. 
OENOCYTES 
The oenocytes of the honeybee have been described by Wielowieysky (52), 
Koschevnikov (27), Anglas (1), and the writer (36). They are very conspicuous 
in sections, on account both of their large size and their great affinity for stains. 
They are rare in the thoracic segments, but are found abundantly throughout 
the abdomen, always occurring singly, never in groups, and generally, if not 
invariably, in more or less intimate contact with fat cells. In mature larvae the 
oenocytes closely approximate the fat cells in size, but this is not true of younger 
larvae. In a larva two days old, for example, the average diameter of the 
oenocytes is about twice that of the fat cells (Pl. 8, D, Oen) . The rate of growth 
of the fat cells therefore greatly exceeds that of the oenocytes. Generally speak¬ 
ing, the oencytes are more or less ellipsoid in form, but modifications of this are 
frequent and of such a kind as to afford plain evidence of the amoeboid, wander¬ 
ing nature of these cells. The oenocyte represented in Plate 8, B, is deformed 
to accommodate itself not only to the two adjacent fat cells ( F, F) but also to a 
blood cell (BIC). It is to be noted that the contour of the fat cells is not evi¬ 
dently altered. Many oenocytes are found with a pointed process at one end— 
evidently a pseudopodium—extending between the adjacent fat cells, as though 
wedging them apart, while other oenocytes possess two such processes which 
are applied to and partially surround one or more of the adjacent fat cells. One 
instance of the amoeboid character of the oenocytes, as seen in sections, was 
particularly striking; here an oenocyte had assumed the form of a crescent 
embracing a fat cell between its horns, thus irresistibly suggesting the movements 
of an amoeba preliminary to ingesting its prey. The oenocytes, however, never 
