182 EXPERIMENTAL INOCULATIONS 



the incisor teeth (fig. 143). A very fine gum-elastic catheter can then be 

 easily passed through the hole in the gag into the stomach. By attaching 

 the needle of the syringe to the open end of the catheter, the fluid can be 

 injected. 



Dogs. Fix the animal on its back, and gag it as described at p. 163. Pass 

 a small cesophageal sound or a rather firm piece of ordinary india-rubber 

 tubing of the size of an ordinary pen-holder into the 

 stomach. Inoculate the culture through the sound or 

 tubing. 



It is often necessary to render the contents of the 

 stomach alkaline before introducing the culture ; this can 

 be done by injecting 1 or 2 grams of sodium bicarbonate 

 dissolved in a little water. 



__ C. Inoculation into the intestines. 1. Open the ab- 



FIG. i43.-Gag for ceso- domen as described on p. 174. 



phageai catheterization. g. Pick up and hold a loop of intestine with a pair of 

 forceps. 



3. Pierce the wall of the loop obliquely with the syringe needle. Inject 

 the material and withdraw the needle at once. 



4. Dab the loop with a sponge soaked in carbolic solution : suture the 

 aponeurosis and then the skin. Paint with collodion. 



D. Rectal injection. The animal must be firmly held by an assistant, 

 then with a stout blunt-pointed needle inject the fluid into the rectum. 



SECTION VI. OBSERVATIONS TO BE MADE ON INOCULATED 



ANIMALS. 



In studying an experimentally-induced disease the symptoms to which it 

 gives rise in the inoculated animal should be observed and recorded day 

 by day. 



A note should be made of the following points : 



1. The local lesion. The presence or absence of a local lesion. The time 

 when it appears. Its situation, extent, nature and the changes which it 

 undergoes. Enlargement of the glands. 



2. Temperature. The temperature should be taken at least twice a day 

 in the rectum, with a thermometer graduated in tenths of a degree centigrade 

 and of a size suitable to the species of animal under observation. The tem- 

 perature must always be taken before inoculating the animal. It is necessary 

 to bear in mind that all animals have not the same normal temperature ; in 

 guinea-pigs, rabbits[, goats, pigs] and cattle 1 the normal temperature varies 

 from 38'5 to 39'5 C., that of horses and asses between 38 and 39 C. and 

 of birds between 41 and 42 C. In small animals, complete immobilization 

 rapidly reduces the temperature which should therefore never be taken with 

 the animal tied to the operating table. A curve of the temperature should 

 be kept. 



3. Weight. Animals must always be weighed before inoculation. A 

 ratio can then be established between the weight of the animal and the 

 quantity of virus which must be inoculated in order to produce sickness or 

 lead to death. In chronic conditions, the animal should be weighed from time 



[* The normal temperature of an adult bovine animal is usually constant in the neigh- 

 bourhood of 38-5 C. ; that of a young calf may vary fro-n 38'9 C. to 40'0 C. with a 

 mean of 39'2-39-4 C.] 



