188.8.131.52. Exposing the viscera (Plates 1, and 8 A and B)
To open the abdomen:
1. Steady the dish with the left hand, and the scissors by resting them against the left thumb on the edge of the dish (Plate 1).
2. Insert one point of the scissors under the overlapping edge of the tergite of A5, on the right side of the body.
3. Cut through the body wall.
4. Continue snipping through the right side, working forwards towards the thorax.
Keep the inner blade of the scissors as far as possible parallel with the side of the insect, thus avoiding thrusting it in deeply and damaging the viscera.
5. Turn the dish clockwise to suit the scissors hand when the corner at the front end of the abdomen is reached.
6. Cut across the broad front of the abdomen to the opposite corner.
7. Then again turn the dish and work down the left side.
8. Turn the dish again when the tergite of A6 is reached.
9. Cut across the tergite, taking great care not to damage the soft organs underneath, and so complete the circuit at the beginning of the first incision.
10. Lift off the roof of the abdomen gently with the point of a needle; it should be free and easily removed.
If it resists, one or more of the infolded parts of the tergites have not been severed. These uncut parts must be found and cut through, using the inner scissors point as a probe while gently lifting the roof with the needle. When it is clear that the roof is free, do not pull it off roughly, but lift it gently with two needles. There may be slight resistance from tracheae, but these will break without doing any damage. If, however, it seems that the internal organs are being pulled out or disturbed, take the roof by its edge with the fine forceps, and with the needle in the other hand break the tracheae, which will show as fine threads stretching between the roof and the organs below. Finally lift off the roof and turn it over. If the work has been done neatly, it will come off in one piece.
11. Examine the underside of the roof (Plate 8C) as it lies in the dissecting fluid.
11.1. the heart, with its closed posterior chamber and its ostioles (there are five pairs, but the anterior pair may have been lost), in the mid-line of the roof;
11.2. the dorsal diaphragm, transparent, but clearly visible, and its attachments to the apodemes of the tergites;
11.3. the pericardial fat cells, large numbers of small, creamy bodies clustered against the heart;
11.4. the dorsal sheet of the fat body forming a pad between the heart and the body wall;
11.5. some of the abdominal muscles may be seen as flat, nearly transparent bands stretched across the tergites.
In preserved bees the heart and dorsal diaphragm occasionally adhere to the viscera and thus tear away from the roof. Having examined all these organs, lay aside the roof, and
12. look at the contents of the abdomen.
12.1. The appearance of the undisturbed viscera is very variable, depending on the state of the alimentary canal (Plate 8, A and B). In a bee which has been confined to the hive for some time, or a young bee which has not yet flown, the rectum is greatly distended by accumulated faeces, the bulk of which are yellow pollen husks (A). If the rectum has been damaged by instruments during the opening operations, some of the faeces will have escaped, and will litter the dissection. If the bee has just returned to the hive after a flight, the rectum will be empty and shrunken to very small proportions; if she has brought home a load of nectar or water, the crop (honey stomach) will be expanded into a large, transparent globe (B); if it is empty it will appear as a small, semi-opaque, pear-shaped body;
12.2. part at least of the ventriculus will be visible as a broad, corrugated tube;
12.3. a loop of the small intestine will be found connected to the forward end of the rectum; its other end, which joins the ventriculus, may not be visible;
12.4. the slender, tangled threads which spread all over the abdomen are the Malpighian tubules;
12.5. in a freshly killed bee, the tracheal sacs will be seen as large bags, silvery with included air (which escapes when a needle point is inserted), obscuring parts of the other organs. In preserved bees the sacs are almost invisible, filmy membranes, the air having been dissolved by the preserving fluid. When air-filled sacs obscure the view, they should be pulled out with forceps.
12.6. Tracheae in large numbers appear as silvery tubules in all parts of the body.
13. Clear away debris (faeces, fragments of tissues, etc.) which collects in the abdominal cavity from time to time during dissection.
This is done by irrigation with clear dissecting fluid, a jet of which is directed into the cavity with the pipette.