256 CORTEX 



5 mms. long, are closed by a single suture with silk thread. 

 The skin incision is then closed by several interrupted sutures. 



With experience, the above operation can be performed with 

 ease in less than 5 minutes. If one is careful not to use an 

 overdose of the anesthetic and avoids tearing any of the large 

 blood vessels or injurying the kidney or liver, the mortality 

 from the operation is practically nil. The animals recover 

 and within several hours appear perfectly normal. In animals 

 dying within 48 hours following the operation, the cause of 

 death is to be attributed to gross mishandling with consequent 

 traumatic shock. 



By skillful technique it is possible to perform a complete 

 adrenalectomy and removal of all the accessory cortical tissue 

 in over 95 per cent of all animals. Occasionally, a slip of the 

 forceps, or failure to include the necessary amount of the 

 connective tissue results in leaving an accessory body. Such 

 unsuccessful operations are detected by the prolonged survival 

 of the animal after cessation of treatment and do not result in 

 self-deception as regards the potency of a tested preparation. 



Food and care of the animals. In order to avoid any varia- 

 tions in the food intake due to changes in the diet, the animals 

 should, when weaned at the age of 20 or 21 days, be placed on 

 the same diet as they receive during the assay period. Any of 

 the well-known diets which furnish all the essentials for normal 

 growth is satisfactory. The diet should be in powder form to 

 permit easy mixture of the hormone preparation with the food. 

 The following modification of the Steenbock diet is suitable 

 for the purpose: 



Grams 



Finely ground yellow corn 2280 



Powdered whole milk powder 1000 



Linseed oil meal 480 



Casein 150 



Alfalfa meal 60 



Sodium chloride 15 



Calcium carbonate 15 



