84 Animal Micrology 



15. When the injection is complete, shut the stop-cock, ligate 

 the aorta, or clamp it with pressure forceps beyond the end of 

 the cannula and then remove the latter. 



16. Place the animal in cold water or cold alcohol for half an 

 hour, then remove pieces of liver, spleen, pancreas, stomach, intes- 

 tine, salivary glands, kidneys, and voluntary muscle and harden 

 in absolute alcohol, or in 10 per cent, formalin. 



17. When sufficiently hardened transfer the objects to ether- 

 alcohol and proceed to imbed and cut in celloidin according to the 

 method already given. Make longitudinal sections of the kidney 

 parallel to its flat surface. Cut transverse sections of liver, 

 stomach and intestine, longitudinal of the muscle, and sections 

 passing longitudinally through the hilum of the salivary glands 

 and spleen. The sections should not be under 30 microns thick. 

 Mount some unstained; stain others in diluted Delafield's hema- 

 toxylin or in hemalum. 



MEMORANDA 



1. Apparatus for Continuous Air Pressure Injections is now provided in 

 many laboratories. If a regular cylinder for air pressure is not present, 

 however, an assistant with a little ingenuity can readily fit up a suitable 

 apparatus. A carboy or large-mouthed bottle which can be tightly 

 corked will answer as a chamber for compressed air, a water tap, or a 

 tank of water elevated to the height of 7 or 8 feet will provide sufficient 

 pressure. By making the proper connections by means of rubber and 

 glass tubing a steady stream of compressed air may finally be conducted 

 to a flask containing the injection mass; the flask works in the same way 

 as an ordinary wash bottle. All corks and fittings must be tightly 

 secured with wire or strong cord. If desired, by adding an extra per- 

 foration to the cork in the air chamber, a mercury manometer may be 

 added to register the amount of air pressure. If a metal caunula is not 

 at hand a glass one may be made as indicated under memorandum 8. 

 In lieu of a stop-cock, use a pinch-cock on the rubber delivery tube. 



2. A Double Injection of the Vascular System may be made by first 

 injecting the blue mass until it is seen to flow from the right ventricle, 

 then detaching the tube which conveys the blue mass, and slipping over 

 the end of the cannula a tube conveying a red mass. This second mass 

 should be in a bottle or flask connected with the pressure bottle by 

 means of an additional tube through the cork of the latter, or the two 

 flasks containing the colored masses may be connected with the tube 



