METHOD OF MAKING COLLODION SACS. 



67 



^^ 







-a 



-d 

 -b 



W 



method has been further improved upon by Harris, whose 

 scheme is briefly given as follows : — 



To the smaller end of a gelatin capsule such as is used by 

 veterinary surgeons (Fig. 33, A), a piece of glass tubing about 

 4 cm. long and 3 mm. in inside diameter is affixed by gently 

 heating the tubing and causing it to adhere (Fig. 33, B). The 

 bore of the tubing is then cleared of obstructing gelatin, the 

 junction of glass and gelatin is painted around with a solution 

 of moderately thick collodion or celloidin and allowed to dry. 

 Then the whole capsule is dipped in the solution, removed, and 

 rotated so as to give a perfectly even coating to the capsule. 

 When set, the capsule is allowed to thoroughly dry, and if 

 necessary is again coated and 

 dried, and is reinforced at 

 three points (Fig. 33, C) and 

 once more dried. The gelatin 

 is removed by filling up the 

 capsule with water by means 

 of a fine bore pipette of the 

 Pasteur type, and boiled a 

 couple of minutes in a pan 

 of water, then the gelatin is 

 sucked out by means of the 

 pipette and the sac is refilled 

 with bouillon. Sterilisation is 

 effected by placing the sac in 

 a tube of broth, sac end uppermost, with enough broth in it 

 to cover the. sac to the depth of 1 cm., and either autoclaving 

 for five minutes under one atmosphere pressure or by steaming 

 for three successive days in the Arnold steriliser. The sac is 

 inoculated by first removing some of its contents (Fig. 33 C) 

 under aseptic conditions, and then introducing a small quantity 

 of the desired bacterium in suspension, or in fluid culture, by 

 means of a sterile pipette ; it is then to be seized with sterilised 

 forceps by the glass shank, and the latter brought in contact 

 with the small flame of a blast lamp and sealed off (see Fig. 33, 

 C). The inoculated sac is next to be tested for tightness 

 by incubating it in a bouillon culture tube, after first washing 

 it thoroughly with sterile water to remove any organisms which 

 may have alighted upon it during the exposure to the air 



ABC 



Fig. 33. 



A. Empty gelatin capsule, actual size. " No. 12 

 Veterinary," P. D. & Co. 



B. Glass tube sealed into end of capsule. 

 Sac ready for insertion, a, b, c, points of 



reinforcement 

 of fluid inside. 



tf, limit for height of the column 



