234 HUMANE TREATMENT OF ANIMALS USED IN RESEARCH 
Illustration A 
Figuee 1. — The Modified Blalock Peess. 
The dog’s thigh is placed in the space marked A. B is a groove to accommodate the femur. 
G is a calibrated knee action spring (from a Buick car). The desired pressure is exerted 
on the thigh by screwing down the bolts, D, until the spring has been compressed the 
requisite amount. 
