132 BACTERIOLOGICAL LABORATORY TECHNIC 



inoculated with the organism he wishes to grow. The ends of 

 the tube are then sealed in a bunsen flame and there being no air, 

 anaerobic conditions are fulfilled, and organisms grow. After 

 colonies appear the tube is broken at a file-mark near the colony 

 and tubes inoculated therefrom. 



Under other methods large Novy jars are used for the reception 

 of petri dishes and test-tubes. From these jars the air is with- 

 drawn, and hydrogen allowed to flow into it. A solution of 

 pyrogallic and sodium hydrate is placed in the bottom of the jar 

 to absorb any remaining oxygen. There are many other ingenious 

 mechanical ways of growing bacteria under anaerobic conditions 

 and the student is referred to works devoted entirely to technique. 



Animal Experiments 



To determine the pathogenicity of bacteria; to measure the 

 strength of toxins and anti-toxins, to standardize anti-toxins, and 

 to recover bacteria in pure culture, it is often imperative that 

 small laboratory animals be used. Guinea pigs, rabbits, and 

 mice are oftenest employed. Strong young animals are the best. 

 Culture toxins and pathological material are introduced into their 

 bodies in various ways. A favorite one is to' shave the abdomen, 

 scour it with soap and water, and then bichloride of mercury, and 

 finally sterile water. With a pair of sterile scissors a small hole 

 is cut in the abdominal parieties and through it a loop containing 

 a drop of culture is run into the peritoneal cavity, or under the 

 skin. With ordinary fluid material, a syringe may be used to 

 inject it directly through the abdominal wall. The animal is 

 carefully weighed, and it is watched from day to day. If it dies 

 an autospy is made on it. 



Other methods consist in injecting fluid culture into the veins 

 of the ear, or into the peritoneum, by means of sterile hypoder- 

 mic syringe. The autopsy should be made carefully, the animal 

 should be thoroughly wet with a solution of bichloride of mercury, 



