8 BURGESS ON THE ANATOMY 



also be made by merely cutting througb the integument near the median line with a 

 razor, and in places, with a fine pair of scissors, and then gently tearing it away 

 on one side, thus leaving the principal organs perfectly uninjured, -and in their natural 

 position. By carefully removing the fat body and the tracheae they will, one by one, 

 gradually become evident.^ A preparation thus made is figured on pi. 1, fig. 2. Of 

 course one single dissection will not show every point, as some organs must be removed 

 in order to get at others beneath them ; thus in fig. 2, all the tracheae, one set of ovaries, 

 the urinary tubes, etc., have been dissected out. It is therefore well to make several dis- 

 sections, each having in view one or two organs more particularly, and the study of the 

 separate preparations will give the knowledge of the whole internal anatomy. Besides 

 these preparations, many sections, some coarse, and some thin, must be made, (as de- 

 scribed in text-books of histology and microscopic technique), and mounted for study with 

 the compound microscope. Many points in the anatomy of small parts of the body, and 

 of course the histology in general, are only to be learned from such preparations. 



The Alimentary Canal and its Appendages. The canal traversing the proboscis 

 opens into a pharynx enclosed in a muscular sac, which occupies much of the lower 

 part of the head. The sac itself is nearly round, and is hung in position by five principal 

 muscles, (figs. 4, 5 and 7), two dorsal {d.m.), two lateral {l.in.), and a frontal {f.m.) which 

 is really a pair of muscles closely united. A more feeble muscle is also inserted on the 

 lower aspect of the sac. The sac itself is very muscular, and shows two principal layers 

 of muscles, an outer, of longitudinal annular fibres, and an inner, of transverse fibres. 

 The pharyngeal cavity extends obliquely upward in the sac, from front to back, and is 

 much broader than high. The floor, or hypopharynx, is convex on each side of a median 

 furrow, (fig. 5, hph.) and somewhat resembles in shape the human breast. The convex areas 

 are dotted over with little papillae, which possibly may be taste organs, although I have not 

 succeeded in making out any nervous supply. The cuticular layer of the hypopharynx is 

 very thick, while that lining the superior wall of the pharynx is, on the contrary, delicate, 

 and is thrown into slight transverse ridges. The suspensory muscles of the pharyngeal 

 sac pierce the muscular layer of the latter, and are attached to its internal wall. At the 

 anterior border of the pharynx is a triangular muscular flap, the epipharynx (fig. 5, ep.) 

 overlying the opening into the proboscis, and serving as a valve to close the latter. 



The pharyngeal sac, as is evident from its structure, serves as a pumping organ to suck 

 the liquid food of the animal through the proboscis, and force it backwards into the 

 digestive canal, the j)rocess being as follows : The proboscis is unrolled and inserted 

 in the nectary of a flower ; at this moment the muscles which suspend the pharynx 

 contract, and its cavity is thus extended, creating a vacuum which must be supplied by 

 a flow of honey through the proboscis, into the pharynx. When the latter is full its 

 muscles contract, the valve closes the aperture to the proboscis, and the honey is forced 

 backward into the oesophagus. The pharynx is then again opened and the same process 

 repeated. To prevent the food being sucked back from the oesophagus, it is probable 

 that some of the numerous fibres in the muscular sac near the origin of the former can, 

 by contraction, close its opening, but in any case as the proboscis presents a free tube, and 



^ This work should, of course, be done under water, the small glass dish, 

 preparation being pinned to the wax-coverfd bottom of a 



