Collodion Capsules 



221 



and that will permit of ready sealing in a flame when neces- 

 sary ; the rounded end is cut off, and the edges are smoothed 

 in a flame. The upper open end of the collodion bag is care- 

 fully fitted over the end of the tube, shrunk on by a gentle 

 heating, and cemented fast with a little fresh collodion 

 applied to the line of union. Novy recommends that 

 a thread of silk be wound around the 

 point of union, to hold the collodion in 

 place and to aid in handling the fin- 

 ished sac. It now appears as in figure 

 64, b. The sac is next filled with dis- 

 tilled water up to the thread, the tube 

 is plugged with cotton, and the whole 

 placed in a larger test- tube containing 

 distilled water, the cotton plug being 

 packed tightly around the smaller 

 tube, so that the collodion sac does 

 not reach the bottom of the large 

 tube, but hangs suspended in the 

 water it contains. The whole is now 

 carefully sterilized by steam. 



When ready for use, a tube of 

 bouillon is inoculated with the culture 

 intended to be placed in the animal, 

 the water in the capsule is pipetted 



out and replaced by the inoculated bouillon carefully intro- 

 duced with a pipet, the constricted portion is sealed in a 

 flame, and the capsule picked up with forceps and intro- 

 duced into the peritoneum by an aseptic operation. 



The collodion capsules may be made of any size. Those 

 for rabbit experiments should be of about 10 c.c. capacity, 

 those for guinea-pig experiments about 5 c.c. By coating 

 large glass tubes they can be made of 500 c.c. capacity, 

 the large bags being useful for chemic dialysis. 



Fig. 64. Prepara- 

 tion of collodion sacs: 

 a, Test-tube constric- 

 ted and cut; b, sac 

 attached to the tube. 



