BLOOD SPECIFIC GRAVITY, ETC. 73 



be previously armed with about 10 cm. length of rubber tube carrying a small 

 point-ended piece of glass tube. Bring the rubber tubing from the pressure 

 reservoir of warm Ringer-Locke to the preparation and, unclamping it but 

 controlling its outflow between finger and thumb of left hand, establish 

 connexion free from all air-bubbles between it and the cannula in the renal 

 artery. The pressure-head may be about 70 cm. of water. The fluid perfuses 

 the kidney and, admixed with blood, escapes from the renal vein cannula and 

 tubing in a rapid stream of drops. Receive this stream in a small shallow 

 beaker, fixing the tubing over the edge of the beaker by modelling clay in such 

 a way that the drops drip from the glass point and are therefore small. See 

 that renal artery and vein are not t\yisted or kinked. Count the drops issuing 

 in 20". Observe the appearance of the kidney. 



VIII. When the rate of outflow seems steady, inject 1 c.c. of ' adrenalin ' Obs. 52. 

 solution 1 in 20,000 into the lumen of the rubber tube attached to the renal -Adrenal extract 



&iUd til ft l*AT1ftl 



artery. This can be done by filling a hypodermic syringe with the solution vessels, 

 (all air-bubbles excluded) and thrusting the needle obliquely through the 

 rubber tubing about 5 cm. from the arterial cannula. 15 div. of the syringe 

 scale = 1 c.c. 



In a few seconds the rate of flow from the venous cannula begins to be 

 less. Observe the no. of drops per 20" from interval to interval. Observe 

 the appearance of the kidney. 



IX. Mix one drop of amyl nitrite with 1 c.c. of Ringer-Locke and inject Obs. 53. 



this, as above, into the arterial tube. After about two minutes the outflow- ^^y^ nitrite 

 , . and the renal 



stream mcreases. ^^33^^^ 



X. Examine the diluted blood in the four test-tubes prepared under § III Obs. 54. 

 of this exercise. Tube (2), though diluted equally with (3), is dark and trans- f arH!^^'^ 

 parent, whereas tube (3) is bright but less transparent, and shows sedimentation. 



The red corpuscles have been largely dissolved in (2) but not in (3). Invert 

 each tube carefully once or twice to redistribute the blood-corpuscles in the fluid 

 without frothing. Fill the shallow glass cell with the blood from tube (2), 

 and place the cell over a piece of newspaper ; observe the degree of trans- 

 parency by looking at the print. Empty the cell and repeat with blood from 

 tube (3) ; and similarly repeat with blood from (1) and from (4). Place a drop 

 of the blood from tube (3) under a microscope ; note that the red blood- 

 corpuscles are well preserved. Repeat with a drop from tube (2). Note that 

 in the laked blood many of the red corpuscles are reduced to * shadows ', 

 * ghosts ', though some are still preserved. The*' ghosts ' may be rendered 



