INOCULATION INTO THE RESPIRATORY PASSAGES 179 



(xiii) Inoculation into the respiratory passages. 



A. Inoculation into the lungs. 1. Shave and cleanse the skin of the thorax 

 in the neighbourhood of the axillary fold. 



2. Push the needle perpendicularly through one of the upper intercostal 

 spaces to a depth of from one to several centimetres, according to the size 

 of the animal. Inoculate the material and withdraw the needle. 



B. Intra-tracheal inoculations (mammalia). 1. Fix the animal on its back 

 with the head extended and the neck raised by means of a firm plug of cotton- 

 wool, a large india-rubber cork or a small block, etc. Shave and cleanse the 

 skin in the middle line below the larynx. 



2. Make an incision 2-3 cm. long through the skin in the middle line of the 

 neck in front of the trachea. 



3. Incise the aponeurosis on a director. 



4. Having exposed the trachea, pass the needle obliquely into the lumen 

 between two of the cartilaginous rings. Inject the material. Withdraw the 

 needle and wash the perforation with a sponge soaked in carbolic water. 



Notes. (a) In small animals it is convenient as soon as the trachea is exposed 

 to fix it by passing a suture needle threaded with silk through it. 



(6) To avoid all risk of inoculating the material into the cellular tissue or into the 

 walls of the trachea itself the following precautions may be taken. Use a small, 

 very fine trocar with a cannula which should be shorter than the syringe needle. 

 When the trachea is exposed pass the cannula between two of the cartilaginous 

 rings, withdraw the trocar leaving the cannula in position. Pass the syringe needle 

 through the cannula so that the point of the needle passes beyond the end of the 

 latter. Make the injection and withdraw the needle first, then the cannula. 



5. Suture the skin. Cover the wound with collodion. 



C. Intra-tracheal inoculation in birds. The opening of the trachea is 

 behind the base of the tongue. 



1. Open the beak and draw the tongue forwards with a pair of forceps. 



2. The opening of the trachea will be seen behind the tongue and the 

 material to be inoculated is injected straight into it. 



D. Intra-pleural inoculation. Besson has shown as a result of some 

 observations which he made with Pourrat that it is a very difficult matter to 

 inoculate a fluid into the pleural cavity without, at the same time, injuring 

 and penetrating the lung. Consequently intra-pleural inoculation is not 

 very exact. 



In those cases where the syringe needle is passed obliquely from below 

 upwards through an intercostal space (6th or 7th) it often happens either 

 that the pleural cavity has not been reached or that the needle has passed 

 beyond it. To perform a true intra-pleural inoculation the following 

 technique must be followed. 



1. After fixing the animal on its left side, shave and cleanse the skin over 

 the middle of the right side of the thorax. 



2. Make an incision about 3 cm. long through the sixth space about its 

 centre parallel to the rib and passing through the skin, subcutaneous cellular 

 tissue and, if desired, the external intercostal muscle. 



3. Have ready a blunt-pointed needle, laterally perforated and previously 

 sterilized and connected to a syringe by means of an india-rubber tube 

 (p. 167). Pass the needle into the intercostal space, directing it somewhat 

 obliquely. The parietal pleura attached to the outer wall of the cavity 

 allows the needle to pass through : the visceral pleura, with the lung, is 

 driven back by the blunt end of the needle and when the latter has gone a 



