ANESTHETIZATION OF ANIMAL 



81 



The operator uses both hands to draw this string tight, 

 and when the first knot is tied the assistant places his right 

 thumb over the knot to hold it tightly while the second 

 knot is tied. Why should this string be tied so tightf/i/ 



Fig. 75. Harvard time clock. 



The average student will probably find out before the first 

 experiment is finished. The towel is now quickly tucked 

 down over the dog's, mouth and nose and a little ether is 

 poured on. The most steady and reliable student in the 



