THE PHENOMENA OF ANTITOXIN FORMATION 65 



advisable that the animal should be bled for antitoxin after a rest 

 of about a week from its last injection. 



The bleedings are carried out at the laboratories of the Royal 

 Colleges of Physicians and Surgeons in the following manner : 

 The receptacles for the blood are 2-pound glass jam-jars, which 

 are sterilized by heat and covered with parchment paper which 

 has been soaked for some hours in i : 20 carbolic. Two layers 

 of this are used, and the lower one has two radial slits cut in it, 

 leaving a triangular wedge, which can be raised and access to the 

 bottle thus obtained. Twelve or fourteen of these are required 

 for each horse, and each is filled about two-thirds full. 



The side of the horse's neck is shaved and washed with a 

 solution of lysol, or a lysol dressing is put on an hour or two 

 before the operation. The horse is placed in the stocks, and if 

 violent the head is restrained by a twitch. It is then necessary 

 to apply pressure at the lower part of the neck, in order to distend 

 the jugular vein ; this may be done by the thumb of an assistant, 

 or, better, by means of a firm leather plug, which is pressed into 

 the groove in front of the sterno-mastoid muscle by means of an 

 arrangement of straps devised by Dr. Cartwright Wood. In this 

 way the vein is temporarily occluded, and stands out clearly 

 above the region where the pressure is applied. The operator 

 (having sterilized his hands as for a surgical operation) then 

 makes an incision about 2 inches long and above or just in- 

 ternal to the vessel ; this should open the deep fascia, but 

 need not actually expose the vein. He then takes a trocar and 

 cannula having a diameter of about T \ inch, and pushes it firmly 

 downwards into the vein ; success in this is shown by the blood 

 oozing up by the side of the trocar. An assistant now stands 

 ready with a short metal tube which fits inside the cannula 

 and communicates with 2 or 3 yards of indiarubber tubing, with 

 a foot or so of glass tubing at its farther end. The whole has 

 been sterilized by being soaked in lysol or carbolic lotion. A 

 second assistant now reflects half of the outer parchment covers 

 of one of the jam-pots, reflects the triangular strip which has'been 

 already cut in the inner cover, and inserts the glass tube in the 

 opening. The operator then removes the trocar, and the first 

 assistant rapidly fits the metal tube attached to the rubber tubing 

 into the cannula; when this is done quickly hardly any blood 

 escapes. The blood now passes through the rubber tubing into 

 the jam-pot, which rapidly fills. When about two-thirds full the 



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