176 



EXPERIMENTAL INOCULATIONS 



conical. After the sac has been sterilized the water is withdrawn with a syringe 

 and the culture introduced. The pointed end is then sealed off in a small flame. 

 Bertarelli further suggests using a solution of collodion in ether of the same 

 consistence as is used for embedding, in place of collodion. 



(ii) Phisalix has introduced a modification of the method of preparation by 

 which much stronger sacs can be made, and the risk of breakage in the abdominal 

 cavity thereby reduced. 



A collodion sac is prepared as above (Stages 1 to 4) and slipped 

 on to a guide consisting of a perforated glass ampoule (fig. 

 141, A). The sac which now covers the guide is fastened to the 

 neck of the ampoule with a few turns of silk thread, and this 

 is covered with a layer of collodion. 



The sac is then sterilized in the autoclave in the ordinary 

 way. After the sac has been filled with the culture the neck 

 of the ampoule is sealed off in the flame (fig. 141, B). 



\ /^^\ (**i) Grorsline noted that the principal difficulty in making 

 collodion sacs is the separation of the sac from the tube on 

 which it is moulded. He overcomes this difficulty by using 

 3D ; CD ^ W:] test- tubes perforated with a small hole in the bottom. In making 

 a sac the hole is first obliterated by gently touching the bottom 

 O D && : f the tu ^ e on *ke collodion. After the sac has then been made 

 in the ordinary way and dried, the tube is filled with water. 

 By blowing down the open end of the tube, the water forces 

 its way through the small hole at the bottom of the tube and 

 A p insinuates itself between the tube and the sac, with the result 



FIG. 141 Phisalix' * nat *^ e l atter i g easily separated. 



guides for collodion () i nser tion into the peritoneal cavity. Collodion sacs 

 may be used in experiments upon guinea-pigs, rabbits, 

 dogs, sheep, cattle [and birds (fowls and pigeons)]. All these animals 

 tolerate aseptic sacs filled with sterile broth very well. The technique of 

 the operation is described above (p. 174, B). 



After an interval varying from a few days to several months, the animal 

 is killed and the sac withdrawn and its contents investigated. When the 

 sac has been in the peritoneal cavity several weeks it not infrequently happens 

 that it is found to be broken ; [even then it is in the case of birds at least 

 usually covered with a fibrous sheath which prevents dispersal of the con- 

 tents]. It is well therefore to use several animals, to be sure of finding at 

 least one sac intact. To remove the contents, sterilize the bottom with a 

 hot wire, insert a pipette and aspirate the fluid. 



D. Reed sacs. Roux and Nocard suggested using, in place of collodion, 

 a, small piece of the tubular membrane lining the central canal of the bul- 

 rush. Sacs made with this membrane are more permeable than those made 

 of collodion. 



1. Take a few pieces of common bulrush and, if they are fresh boil them in 

 water for about a quarter of an hour, but if dry autoclave them at 115 C. for an 

 hour instead. 



2. After softening them sharpen one end in the same way as a lead pencil, in 

 order to expose the membrane lining the central canal. This membrane is then 

 carefully denuded for a certain length. 



3. Tie one end of the separated membrane firmly like a purse, then by pressing 

 gently on this end with a glass rod it can be turned inside out. 



4. Tie a small glass tube into the open end and fasten it with a stout ligature, 

 and place another ligature on the sac itself below the end of the tube. Fill the 

 sac with water and sterilize as in the case of collodion sacs. 



5. Suck up the water out of the sac and replace it with the culture, tie the ligature 

 on the reed and disconnect the sac from the tube above this ligature. Cover each 

 ligature with a drop of melted gum lac. 



Introduce into the peritoneal cavity in the manner already described. 



