COIiLODroM SACS. 501 



side of the linea alba, through, the abdominal wall to the peritoneum. 

 A grooved sound is then introduced into the cavity and the periton- 

 eum is opened. The abdominal wall on each side of the incision is 

 seized with a pair of pressure forceps, so that by crossing the forceps 

 the cavity can be closed. 



By means of a pair of forceps, the sac is picked up, at the 

 threaded portion, and inserted into the abdominal cavity. The ab- 

 dominal wall is then sewed by means of a. curved needle. An assist- 

 ant should hold the forceps so as to bring the cut edges together and 

 have the walls on a stretch. When the abdominal wall has been 

 closed the ends of the silk thread are cut off and the wound disin- 

 fected with a piece of filter-paper soaked in mercuric chloride. The 

 skin is then sewed in like manner. The surface about the wound is 

 disinfected, then washed with absolute alcohol and dried with sterile 

 filter-paper. A few tufts of absorbent cotton are spread over the 

 incision, after which collodium is applied and smoothed down with 

 forceps or knife. When this has thoroughly dried the animal can be 

 returned to its cage. 



The sac is allowed to remain in the animal for from 3 to 5 days 

 although, in special cases, it may remain for several months. When 

 it is desired to remove the sac the animal is placed under a bell-jar 

 and ether or illuminating gas is introduced. When the animal is dead 

 it is spread out on a board (see p. 276) and opened. The sac will 

 usually be found buried among the intestines and surrounded by ad- 

 hesions. It should be carefully removed and the fibrinous covering 

 stripped off. It is then placed in the sterile test-glass (Fig. 43), with 

 the glass end down. A hot glass rod or searing iron (Fig. 48 a, p. 275), 

 is then applied to the end of the sac and an opening is thus burned 

 through. The milky contents of the sac are then drawn up into a 

 sterile bulb pipette. Transplantations can be made to the various 

 nutrient media or another sac may be inoculated. The end of the 

 pipette can then be sealed and the liquid preserved for subsequent 

 examinations. 



, It is understood, of course, that all the instruments, etc., used in 

 the operation must be sterile. They are sterilized by boiling in a 

 saturated solution of borax (Fig. 48 6, p. 275). The hands of the oper- 

 ator should be thoroughly scrubbed with soap and water and then im- 

 mersed for some minutes in mercuric chloride solution. 



