70 METHODS OF MICROSCOPICAL RESEARCH. 



tion requiring much dexterity of manipulation, 

 considerable practice, some experience and great 

 care, the student must not be discouraged by 

 disappointments and failures, but persevere until 

 success is attained. It is advisable to practise with 

 cold aqueous fluid media, and this operation being 

 successfully accomplished, to go on to injections 

 with the warm gelatine "mass." It will be found 

 best, also, to commence by injecting the organs of 

 animals, such as the kidney, liver, lung, large and 

 small intestines, &c., of the cat, the sheep, or the 

 pig, the eye of an ox (from the artery), and by 

 complete injections (from the aorta), of small 

 animals, e.g., rat, guinea-pig, rabbit and frog, 

 before attempting to inject a whole animal. 



The kidney should be singly injected with 

 carmine mass through the artery, and a double 

 injection should also be made with carmine from 

 the artery, and with blue from the vein. 



The liver in like manner may be injected from 

 the portal and hepatic veins and from the bile ducts 

 (thus ligature the common bile duct, remove 

 the fundus of the gall bladder, remove as much bile 

 as gentle pressure will force out, affix the cannula, 

 and inject). 



In injecting isolated organs removed from the 

 body of an animal, the greatest care must be taken 

 to tie all divided vessels, and to use no more than 

 the necessary pressure upon the piston of the syringe. 

 The slower and more gradual the flow of the fluid, 

 the more perfect will be the injection. 



All animals, or " parts " to be injected with a 

 gelatine mass must be placed in warm water of a 

 temperature from 40 to 45 C. during the process. 



