THE PIGEON. 219 



XXIII. Ligature the pectoral vessels, if the subject is 

 not injected : cut through the origin of the sub- 

 clavius and reflect it : cut away the greater part of 

 both pectoralis and subclavius, leaving a recognis- 

 able portion of the anterior end of each still 

 attached to the upper arm : do the same on the 

 other side,, thus exposing the whole sternum as 

 well as the greater part of the coracoids and 

 furcula: make a longitudinal cut, with strong 

 scissors, through one side of the sternum parallel 

 and close to the keel, and extending to about the 

 middle of the latter : gradually cut or break away 

 the posterior part of the body of the sternum 

 external to this incision until the following 

 structures can be seen : 



169. The anterior-intermediate air-sac, immediately 

 in front of the corresponding postericrr-intermediate (§ 160). 



170. The falciform ligament, a median vertical sheet 

 of peritoneum, attached along the middle line of the sternum, 

 and passing dorsalwards among the viscera (§ 185). 



to escape. Remove the corpus sterni on the same side, so as to expose 

 the heart and see the origin of the pectoral vessels (§ 168) : insert a 

 cannula into the pectoral artery through the incision ah-eady made, tie 

 securely, and inject towards the heart : in this way the whole of the 

 arterial system is filled. The systemic veins may be injected from the 

 pectoral vein, but better results are obtained by injecting from the 

 coccygeo- mesenteric vein (§ 197), the cannula being injected baclcwards, 

 or towards the renal portal veins : the severed pectoral vein should first 

 be tied or clamped with bull-dog forceps. It Avill probably be found 

 necessary to inject the precavals (§§ 243, 245) and their feeders separately : 

 tbis is best done by making an incision in one of the jugulars (preferably 

 that of the side on which the pectorals iave already been cut) near its 

 proximal end, and injecting forwards. The portal system is best 

 injected from the coccygeo-mesenteric vein (§-197), the cannula being 

 directed forwards. 



