174 THE MICROSCOPE 



Injecting a Green Lizard.— Render the animal insensible with 

 chloroform ; lay bare the heart, taking care not to injure the epi- 

 gastric vein ; slit open the pericardium, and cut off the apex of 

 the ventricle. When the bleeding has stopped, push a cannula 

 through the wound into the cavity of the ventricle, and thence 

 into the right aorta, and tie it in place by a ligature round the 

 base of the ventricle. A warm solution of gelatine, covered with 

 carmine, vermilion, or French blue (ultramarine), is the best 

 injecting medium. It is firm enough to pass through capillaries, 

 so that the whole vascular system, with the exception of the pul- 

 monary vessels, can be injected at one operation. 



Injection of Pigeon.— As soon as the bird is dead (kill with 

 chloroform or potassic cyanide), pluck the breast, expose the pec- 

 toral vessels of one side, cut through these vessels as near as pos- 

 sible to the reflected pectoralis major^ and allow to bleed. All 

 this must be done very quickly, as birds' blood coagulates very 

 fast, and it is essential to success to allow as much as possible to 

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

 expose the heart, and see the origin of the pectoral vessels. Insert 

 a cannula into the pectoral artery through the incision already 

 made, tie securely, and inject towards the heart. In this way the 

 whole of the arterial system is filled. The systemic veins may be 

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

 injecting from the coccygeo-mesenteric vein, the cannula being 

 inserted backwards, or towards the renal postal veins. The 

 severed pectoral vein should first be tied or clamped with bull-dog 

 forceps. It will probably be found necessary to inject the pre- 

 cavals {vena cava superior, anterior dextra, a large vessel, situated 

 dorsal and external to the right innominate artery, formed by 

 union of jugular, trachial, and pectoral) and their feeders sepa- 

 rately. This is best done by making an incision in one of the 

 jugulars (preferably that of the side on which the pectorals have 

 already been cut), near its proximal end, and injecting forwards. 

 The postal system is best injected from the coccygeo-mesenteric 

 vein, the cannula being directed forwards. 



Injection of Rabbit.— Kill with chloroform or potassic cyanide. 

 As soon as it is dead, oi)en the thorax by cutting through the 



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