MECHANISM OF SECRETION IO5 



tains secretin, which has the effect of producing a rapid flow of 

 pancreatic juice when injected into the circulation. 



2. Inject pilocarpine nitrate and compare the effect with that of 

 secretin. 



The mamma. A lactating animal (cat) is anaesthetised and a 

 cannula tied into the external jugular vein. Vaseline the fur over 

 one of the mammae, and arrange the animal so that this gland slightly 

 overhangs the edge of the animal board. Cut away the nipple of that 

 mamma and make a short transverse incision into the substance of 

 the gland. Still any bleeding with cotton- wool or with dilute supra- 

 renal extract. Some milk may ooze out : it will run down the 

 vaselined fur, and can be caught in a beaker. 



1. Inject into the vein 1 c.c. of a 10 per cent, decoction of corpus 

 luteum (filtered). Milk will, in a minute or two, exude and drop 

 rapidly from the gland. 



2. Inject into the vein 1 c.c of a 10 per cent, decoction of posterior 

 lobe of pituitary body. The same result will ensue, but the flow will 

 be more rapid. 



The kidney. In an anaesthetised rabbit or cat tie a cannula into 

 the jugular vein and connect the carotid with a manometer for register- 

 ing blood-pressure. Make an incision through the skin and muscles 

 on the left side of the abdomen near the back over the situation of 

 the kidney, which is easily felt. After exposing the kidney, bring it 

 towards the surface, partly clear it of fat, and allow it to lie in a 

 suitable plethysmograph (Fig. 72), the margins of which have been 

 vaselined, and place over it a glass cover also well vaselined : the cover 

 is clipped down on to the plethysmograph. The blood-vessels and 

 ureter pass out at the chink (g) left on one side of the plethysmograph : 

 the chink is made airtight with vaseline. A tube leads from the 

 plethysmograph to a piston recorder (p.r.) writing on smoked paper. 

 Make another incision in the lower part of the abdomen in the middle 

 line ; find the urinary bladder ; hold it up with two pairs of clamp 

 forceps; loop a ligature round it just outside these; make an incision 

 into it, and introduce a glass cannula, which must then be tied in. 

 The urine can be led from this cannula over the side of the animal by 

 a rubber tube, and the drops can be registered by a drop-recorder. 



1. Inject pituitary extract into the vein, and record the effect on 

 blood-pressure, kidney-volume, and urine. 



2. Inject a few milligrammes of caffeine citrate into the vein, and 

 record its effect in the same way. 



3. Inject atropine sulphate (5 milligrammes). This has no effect on 

 the secretion of the kidney (compare with its effect on salivary 

 secretion). 



