140 INOCULATION OP ANIMALS 



breathing, etc. The temperature is usually to be taken. This 

 is generally done per rectwm. The thermometer (the ordinary 

 clinical variety) is smeared with vaselin, and the bulb inserted 

 just within the sphincter, where it is allowed to remain for a 

 minute ; it is then pushed well into the rectum for five minutes. 

 If this precaution be not adopted a reflex contraction of the 

 vessels may take place, which is likely to vitiate the result by 

 giving too low a reading. 



Collodion Capsules. — These have been used to allow the 

 sojourn of bacteria within the animal body without their coming 

 into contact with the cells of the tissues. Various substances 

 in solution can pass in either direction through the wall by 

 diffusion, but the wall is impermeable alike to bacteria and 

 leucocytes. The following method of preparing such capsules is 

 that of M'Rae modified by Harris : A gelatin capsule, such as 

 is used by veterinary surgeons, is taken, and in one end there 

 is fixed a small piece of thin glass tubing by gently heating the 

 glass and inserting it. The tube becomes fixed when quite cold, 

 and the junction is then painted round with collodion, which 

 is allowed to dry thoroughly. The bore of the tubing is cleared 

 of any obstructing gelatin, and the whole capsule is dipped into 

 a solution of collodion so as to coat it completely. The collodion 

 is allowed to dry, and the coating is repeated ; it is also advis- 

 able to strengthen the layer by further painting it at the 

 extremity and at the junction. The interior of the capsule is 

 then filled with water by a fine capillary pipette, and the capsule 

 is placed in hot water in order to liquefy the gelatin, which 

 can be removed from the interior by means of the fine pipette. 

 The sac is filled with bouillon and is placed in a tube of 

 bouillon. It is then sterilised in the autoclave. A small 

 quantity of the bouillon is removed, and the contents are 

 inoculated with the particular bacterium to be studied, or an 

 emulsion of the bacterium is added. The glass tubing is seized 

 in sterile forceps,' and is sealed off in a small flame a short 

 distance above the junction. The closed sac ought then to bo 

 placed in a tube of sterile bouillon to test its impermeability. 

 The result is satisfactory if no growth occurs in the surrounding 

 medium. The sac with its contents can now be transferred to 

 the peritoneal cavity of an animal. 



Autopsies on Animals dead or killed after Inoculation. — 

 These should be made as soon as possible after death — in fact, 

 it is preferable to kill the animal when it shows serious signs of 

 illness. It is necessary to have some shallow troughs, con- 

 structed either of metal or of wood covered with metal, conveni- 



