106 THE MICROSCOPE 



the stop-cock can be turned, and thus the tube will be charged 

 without containing air. Choose now cannulse of a suitable size to 

 the vessel you intend to inject into. Dr. White recommends the 

 specimen, after being saturated with the glycerine from the inject- 

 ing fluid, only requires a little weak glycerine and camphor water 

 to put it up in. It preserves many features that otherwise would 

 have been blotted out. 



A simple Injecting Apparatus is that shown in PI. XIV., Fig. 

 2, the construction of which may easily be seen. The stop-cock {d) 

 should fit into the aperture of the cannules of the ordinary injecting 

 apparatus. The cannules should be tied into the vessel of the 

 organ to be injected, and placed in a convenient position near the 

 glass tube, having been previously filled to a certain height, and 

 the stop-cock turned off. Insert the end of the tube securely into 

 the aperture of the cannule and open the cock. The original 

 pressure may be maintained or increased, as necessity may 

 require. Its advantages are simplicity and that it may be left to 

 itself for a number of hours or even days. 



The most usual way of injecting the blood-vessels is by means of 

 the ordinary syringe. This requires a great amount of practice. 

 The animal has to be kept in hot water ; the mass has to be kept 

 hot usually in a separate vessel, and time has to be allowed 

 between each syringeful for the fluid to penetrate. Then, again, 

 if air gets in on introducing the point of the syringe into the 

 socket of the pipe that is tied into the artery, the fluid will not 

 run at all. 



Fearnley's Apparatus.* — With this method no practice is 

 required beyond introducing and tying in the nozzle in the 

 aorta. There is a bath which has a shallow part for the animal 

 to lie in and a deeper part for the WoulfPs bottle, containing the 

 injection mass, to stand in. A large (40 oz.) Woulft's bottle, with 

 three necks, is fitted with three perforated india-rubber stoppers. 

 The middle stopper is fitted with a glass tube, which goes to the 

 bottom of the bottle. Each of the others is fitted with a glass 

 tube the depth of the stopper only, and standing above the 



* The accompanying engraving is given through the courtesy of Messrs. 

 Swift and Son. 



