158 EXPERIMENTAL PHARMACOLOGY 



a one per cent solution and fill the tube. Similarly fill the 

 other three tubes with the mixture, but place in the second 

 tube ten per cent of alcohol, in the third, forty per cent, 

 and in the fourth, seventy per cent. Be sure the air is all 

 out of the tops of the tubes. Place these in an incubator 

 at 37 degrees Centigrade (or in a warm room) until the 

 next day. Then examine the tubes and record any obser- 

 vations you may make. A culture of colon bacilli may be 

 used instead of yeast. 



EXPERIMENT XVI. 



Alcohol, Brandy, Urethane, Chloral. (Dog: Blood-pressure, 

 Respiration, Cerebrospinal Fluid, Kidney or Spleen.) 



1. Etherize a dog and arrange for blood-pressure and 

 respiratory tracings. Provide two injecting burettes (one 

 containing adrenaline, the other twenty per cent alcohol). 

 Turn the dog's head to the left, trephine the skull (see 

 Figs. 97 and 100; also read Experiment V, 2, page 103). 

 Make the trephine opening in the skull as carefully as pos- 

 sible so the edges will be smooth and regular. With small 

 scissors cut away the dura mater over the area covered 

 by the opening. Do not injure the brain and try to avoid 

 all hemorrhage. NOAV place a perforated (rubber) cork 

 tightly in the opening so that solutions cannot leak around 

 it. The cork must not press on tlie brain. The perfora- 

 tion in the cork carries a small (5/16 inch) glass tube. 

 This tube is filled Avith salt solution and then connected 

 by rubber tubing to a small water manometer (Fig. 151). 

 From the funnel the manometer and tubing are filled with 

 normal salt solution, the glass tube in the cork is filled 

 with salt solution from a pipette, and the rubber tube is 

 slipped over the glass tube. This makes a complete fluid 

 connection between the cerebrospinal fluid in the subdural 

 spaces and the meniscus of the salt solution in the left 

 hand limb of the manometer. For adjustments in pres- 



