108 THE MICROSCOPE 



Stopper sufificiently to admit of a piece of india-rubber tubing 

 (such as is used with infants' feeding bottles) being fixed upon it. 

 The Woulff's bottle containing the mass has two necks, fitted with 

 india-rubber stoppers. One neck admits a piece of glass tube, 

 which goes quite to the bottom of the bottle. The other admits 

 a short piece of tube, the depth of the stopper only. The illus- 

 tration shows all further detail. The apparatus is made by Messrs. 

 Swift and Son. The mercurial manometer allows five inches 

 rise of mercury in the ascending arm, therefore five inches fall in 

 the descending arm, though four inches will do. To inject the 

 animal, proceed as follows : — Fill the bath with water, and heat 

 the water with a Bunsen burner to loo*^ Fah. or so. The Woulffs 

 bottle containing the mass should be filled and thoroughly stop- 

 pered. Then chloroform the animal and make an L-shaped inci- 

 sion into the thorax, so as to expose the heart and aorta. This is 

 done by passing the knife up the middle line of the sternum 

 nearly as far as the root of the neck ; then make a second inci- 

 sion at right angles to this to the left of the animal. A triangular 

 flap is thus made, and the heart enclosed in the pericardium 

 exposed. Cut through the pericardium, seize apex of heart with 

 forceps, snip it off. Thus the right and left ventricles are opened, 

 and the animal instantly bleeds to death. The opening in the 

 right ventricle leading to the pulmonary artery has a crescent 

 shape or slit-like appearance ; whilst the opening in the left 

 ventricle, leading to the aorta, is round. Therefore, if desired to 

 inject the etitire arterial system, we insert our nozzle into the 

 round hole ; if the pubno7iary system, into the crescentic slit. 

 The nozzles are to be inserted into one or other of the two holes 

 (usually the round one" to inject the entire arterial system with 

 carmine and gelatine mass). We can now tie either artery only 

 or the whole heart substance. In either case, a ligature oi floss 

 silk is to be used and tightly tied and secured. Now wash all the 

 blood out of the cavity of the thorax to keep the bath-water 

 clean ; lift the animal into the bath and let it remain ten minutes 

 or so to get well warmed. It is useful to slit open the entire 

 abdomen in the median line, so as to allow the warm water to 

 get freely around the viscera. The mass thus gets into every 

 organ and every part of an organ evenly. Now connect the pres- 



