334 
Tmnsactioris of the 
TiVIonthly Microscopical 
L Journal, June 1, 1869. 
is drawn from this first preparation, mounted in September, 1865. 
Like most glycerine preparations, especially thick ones, it did not 
at first reveal all its beauties of detail, and was put aside as a 
failure. It was not until after a long time, nearly a year, that I 
considered the slide to be of any particular interest. I then found 
that many structural peculiarities which had escaped me in the 
usual preparation were distinctly shown. 
In studying the structure of the proboscis, it is weU to com- 
mence with the examination of a recently-killed insect. If chloro- 
form is used as a means of death, the proboscis will almost invariably 
be found in an extended condition ; and, by attaching the fly 
by means of gum to Beck's disc-holder, it can readily be placed in 
any position, and examined by reflected light. Very profitable use 
can also be made of an adaptation of Mr. S. J. Maclntire's cork 
cells,* in which a fly can bo kept, and its manner of feeding 
watched, by careful management, with a 2-inch or 1 J-inch objective. 
The colour and texture of the tissues of the proboscis are, however, 
^singularly unfavourable for examination by reflected light ; therefore 
if any knowledge of internal structure is required, it is necessary to 
resort to dissection or some mode of preparation. Most of my own 
specimens have been prepared by soaking the recently-killed flies in 
glycerine, and leaving them there until required for examination. 
They have usually been mounted in the same fluid in various positions, 
and such specimens show the muscles and chitinous endo and exo 
skeleton with considerable clearness. When, however, a good view of 
the skeleton is desired, a short boihng in caustic potash and mounting 
in a solution of chloride of calcium will give good results. I have 
usually avoided any undue compression in mounting the proboscis, 
excepting where it has been necessary to make a very thin pre- 
paration for observation with high powers. Mr. Boss's 4-inch 
objective has done good service in enabhng flies to be conveniently 
watched in the large glass-topped boxes, which make admirable 
breeding-cages. 
In describing my drawings, I can do little else than follow the 
papers of Mr. Lowne and Captain Lang, who with myself were, until 
recently, working apart and unknown to each other. The skeleton 
consists of a large, hollow, triangular piece (Plate XV., Fig. la). 
The fulcrum, having two hooked processes at its posterior extremity 
serving as an attachment to two powerful extensor muscles (repre- 
sented in situ in the same plate), as well as a comphcated muscular 
system belonging to the posterior joint. Some of the muscles much 
lacerated are seen forced through the membranous envelope in 
Plate XIII., on the right-hand side, just above the maxillary palpi.t 
* ' Journal of the Quekett Microscopical Club/ July, X868, p. 69. ' Monthly 
Microscopical Journal,' April, 1869, p. 203. 
t This figure has accidentally been drawn in an inverted position. 
