ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 



1093 



and shows more of the table than of the apparatus which it 

 supports.) 



The two indiarubber balls Dji underneath the table are raised or 

 lowered by means of a pulley arrangement E. The tap H allows 

 the apparatus to be brought into connection with one or other of the 



Fig. 258. 



balls, the upper one then communicating with the air. The object O 

 and the vessel with the injecting fluid Jfl are both placed in a metal 

 pan sunk in the table and filled with water, and can be kept warm 

 by a gas-jet (tap at G). The table is free, and everything is close at 

 hand for almost instantaneously altering either heat or pressure. 



The original explanation is a little meagre as to the action of the 

 apparatus. 



Simple Method of Injecting the Arteries and Veins in small 

 Animals.* — The principle involved in Prof. H. F. Osborn's method 

 is that by the use of two injecting fluids, of difierent densities, one 

 passing through the capillaries, the otl'.er arrested at the capillaries, 

 the whole vascular system may bo injected from the aortic arch. 



The application of the principle is as follows: — (1) The animal 

 is immersed in tepid water and the heart is uncovered. (2) The apex 

 of the single ventricle, in the case of an amphibian, or of the left 

 ventricle in the case of higher animals, is then laid widely open and 

 the blood allowed to flow freely from the auriculo-ventricular 

 aperture (see V in fig. 259). (3) A cannula is then inserted a short 

 distance into the arterial bulb and the first ligature is fastened around 

 the nozzle. The second ligature is then made ready around the baso 

 of the ventricle, thus surrounding the auriculo-ventricular apertures. 

 (4) An ordinary gelatin injecting mass, stained deep red or purple, 

 is in the meantime prepared. When tlie body is thorouglily warmed, 

 this mass is slowly injected. As the second ligature is still loose, u 

 • Amcr. Natural., xix. (1885) pp. 920-1. 

 Ser. 2.— Vol. V. 4 B 



