Collodion Sacs 713 
the required length of time the animal is etherized. The peritoneal 
cavity is opened aseptically and the sac removed. 
If the sac has been in the animal body for weeks it is surrounded 
with a fibrous sheath. In this case the sheath is removed before the 
sac is opened. 
The bottom of the sac is sterilized by means of a red hot searing 
iron, wire or glass rod. With a bulb pipette the content, which is 
milky in color, is removed, examined and resaced or cultivated in vitro 
or used for classroom work. 
By this method the virulence of micro-organisms may be enhanced 
markedly and it is advantageously used to bring out capsule formation, 
especially when the germs are so attenuated that their pathogenesis 
cannot be exalted, as may be the case of Micrococcus Tetragenus, Micro- 
coccus Pneumonia and others. 
These cocci and B. Pneumonia (Friedlander’s) under this condi- 
tion form enormous capsules which can be used for classroom work. 
Purdue University. 
