18. He now proceeds more gradually to cut through the muscular envelope as shown at H in Fig. 2, taking light strokes with the scalpel and cutting only a slight depth each time.
19. If the muscular envelope cannot be held firmly enough by the pressure of thumb and finger so the knife will cut well the muscle may be hooked with the tenaculum and thus held by the assistant while the operator cuts.
20. Soon a small white bead appears in the bottom of the incision as shown at L in Fig. 2. There is no mistaking this as it is the white sac itself pushing through a very small opening which has been made through the envelope.
21. This opening is now carefully increased by turning the dull side of the scalpel toward the protruding sac and cutting away from it, first on one side and then on the other.
22. The sac keeps pushing outward more and more until it is about the size of a pea. The cutting is then stopped.
23. Now by means of the extracting forceps the sac is gradually lifted by raising it a little on one side and then on the other. The object is to work the sac through the small opening without tearing it by too violent a pull and without lacerating it by gripping too hard with the forceps. The proper way is to grasp lightly and pull gently here and there at its base.
24. When half the sac has been worked through the opening the sac suddenly pops up out of the gizzard-like envelope.
25. The sac is now lifted carefully by the extracting forceps to see that it is all clear and attached only by the discharge duct.
26. If any slight muscular tissue is found clinging to the sac it may be torn away with the sound or tenaculum or carefully cut with the scalpel.
27. The duct, which alone holds the sac, is now clamped in the automatic forceps as near the sac as feasible as shown in Fig. 3.