54 



EXPERIMENTAL PHARMACOLOGY 



the jar. The ether vapor will fill the jar and the frog will 

 presently begin to show symptoms from the action of the 

 drug. Watch the animal closely. Are there pupillary 

 changes? Can you distinguish such stages as that of im- 

 perfect consdmisness, excitement, and anesthesia in the 

 symptoms exhibited by the frog? Touch the animal from 

 time to time and when all the reflexes have disappeared, 

 remove it from the jar and quickly fasten it down to a 

 frog board (Fig. 46) with clips, in the position shown in 

 Fig. 47. Do not injure the animal by unnecessary pres- 

 sure. Place a small piece of cotton over the frog's nose 

 and mouth and pour a few drops of ether on the cotton. 



Fig. 46. Frog board and clip (Harvard). (See chapter on shop work.) 



With small scissors quickly make a median longitudinal 

 incision in the skin above the brain. With the sharp point 

 of a scalpel, held in the same manner as one holds a pen 

 in writing, make a series of short shallow cuts in the skull 

 directly in the median line over the cerebrum (Figs. 47 and 

 48). When an opening has been made through the skull, 

 the sharp point of a small pair of scissors may be care- 

 fully inserted and the opening thus cut larger. Be careful 

 not to injure the brain. Check hemorrhages with small 

 plugs of cotton. Expose both lobes of the cerebrum and 

 then with the point of the scalpel carefully remove from 

 behind forwards the entire cerebrum. Check hemorrhages 

 with cotton plugs for a while, but do not compress the optic 



