172 



EXPERIMENTAL INOCULATIONS 



made to stand out. A fine needle is introduced obliquely into the sac from 

 above downwards and the material injected. 



B. The posterior limb sacs. Introduce a needle obliquely from above 

 downwards under the skin below the femoro-tibial joint and inject the 

 material. 



(v) Intra-muscular inoculation. 



1. Shave and cleanse the part. 



2. Push the needle deeply into the muscles, inject the material and with- 

 draw the needle. 



Inoculations are made for preference into the muscles of the thigh in the 

 mammalia, and into the pectoral muscles of birds. 



(vi) Intra-venous inoculation. 



Whenever possible intra-venous inoculation should be made into a superficial 

 vein. The needle may be passed through the skin directly into the vein 

 without first exposing the latter. Intra-venous inoculation cannot be effected 

 in the case of very small animals such as mice. 



A. Rabbits. 1. One of the dorsal veins of the ear, and, for preference, 

 the external marginal vein should be selected. Avoid the median veins, 

 because, being embedded in a lax cellular tissue, they are liable to slip away 

 from under the needle. 



2. Cut the hair over the vein with a pair of curved scissors [or better, shave 



FIG. 138. Pressure forceps for the ear vein. 



it], and cleanse the skin. The rabbit is placed on the operator's knee and, 

 if necessary, held by an assistant. 



3. Take hold of the margin of the ear between the index finger and thumb 

 of the left hand so as to extend it. Put a pair of pressure forceps on the 

 vein at the base of the ear so as to make the vein prominent (fig. 138). 



By rubbing the skin with a sponge 

 soaked in warm carbolic water the vein 

 can be rendered more distinct. 



4. Hold the needle very obliquely, al- 

 most parallel to the vessel and pierce it 

 in the direction of the blood-stream 

 (fig. 139). 



5. When the needle is in the vein, take 

 off the forceps and inject the fluid slowly. 

 It is a good plan to apply the forceps higher 

 up on the needle itself, so as to hold it 

 in the skin. If the needle has missed the 



^ vein, the injection will cause a sub- 



/ M^L-^^_ ^ cutaneous swelling, and the operation 



S must be begun again lower down. 



After the fluid is injected withdraw the 

 needle, and if the vessel bleed leave the 

 forceps on the bleeding point for a few minutes, [or pass the vein between 

 the finger and thumb moving them against the blood-stream]. 



B. Guinea-pigs. The superficial veins are not large enough in the guinea- 



FlG. 139. Inoculating into the ear vein 

 of a rabbit. 



