434 
PROF. B. T. LOWNE ON" THE STRUCTURE AND 
With regard to the histology of these glands, very little, if 
anything, can he said to have been recorded of a satisfactory 
character. Stein gives several very remarkable figures ( l . c. 
pi. ix. figs, i, v, and xii) of their histological structure, with the 
following description : — 
“ The fine structure of the glands is nearly the same in all 
Beetles ; they belong to that class of glands which yield a 
fluid secretion, and which are tubular, follicular, or exhibit 
bladder-like cavities. In the gland-follicles the proper elements 
of the gland form a manifold layer of nucleated cells which pre- 
pare the secretion. Between these cells very fine wavy canals 
spread into the follicles, formed as outgrowths of the epithelial 
coat (of the central cavity), and terminate either in blind ends or 
within the cells *. 
“ In general the contour of the gland-follicles is the same as 
that of the epithelial coat of the central cavity The 
secreting-cells lie between the epithelial and peritoneal coats [the 
italics are mine] without order, near and over each other, and 
not united together. In form they are round, oval, or egg- 
shaped ; in the latter case the blunt end is turned outwards, and 
the outlines of the cells, when one examines the entire follicle 
under a certain pressure, are not generally distinctly seen, so 
many lie over each other, and the cells, owing to their granular 
contents, are so opaque ” (pp. 102, 103). 
Leuckart (16a), in his memoir on the Pupiparae, gives a 
figure of the corresponding gland of Melophagus ovinus , which, 
although on a much smaller scale, represents a similar appear- 
ance, and gives a description which corresponds nearly with 
Stein’s. 
These figures and descriptions are very difficult to understand, 
except on the supposition that both Stein and Leuckart examiued 
glands with a quantity of adherent fat-cells. The fat-cells of the 
ovary form a large mass on its posterior aspect, and closely sur- 
round and adhere to the gum-glands. These fat-cells, when half 
empty, as they always are in the egg-layiug female, exhibit 
* “Zwisehen diesen Zellen verbreiten sicb am Follikel sehr feine geschlan- 
gelte Kanale welche von Austulpungen der Epithelealkaut gebildet werden, und 
die nach aussen entweder blind endigen, oder an einer Zelle endigen.” 
