244 CORTEX 



mized animals, expressed in terms of rat units. The rat unit 

 as defined in the next chapter is the amount of hormone neces- 

 sary to maintain normal growth in a 30 day-old adrenalecto- 

 mized rat. The requirement for maintaining growth in a 

 young animal as compared with the requirement for maintain- 

 ing life in an adult of the same species is out of all proportion 

 to their relative weights. Thus, whereas one rat unit is neces- 

 sary for maintaining growth in an immature rat weighing 30 

 grams, it requires only 3| rat units to maintain life in an adult 

 rat weighing 250 grams. Likewise, the requirement for main- 

 taining growth in a one-kilogram puppy was found to exceed 

 the average dose necessary for maintaining life in adult dogs 

 weighing 5 to 15 kilograms. 



The last column of Table 2 shows that the adrenal cortical 

 requirement of mice, rats, cats, and dogs is roughly propor- 

 tional to their surface areas. This proportionality is remark- 

 able when we consider the wide individual variations which 

 one encounters in different animals of the same species. Since 

 the surface area is roughly proportional to the active mass of 

 an individual and to his metabolism, it is not inconsistent that 

 the adrenal cortical hormone requirement should also be pro- 

 portional to this body function. If we assume the validity of 

 this proportionality, the data on mice, rats, cats, and dogs 

 permit us to estimate the human requirement as being about 

 220 rat units per day. This amount will probably seldom be 

 necessary clinically since the diseased individual, unlike the 

 experimental animal, still possesses some residual adrenal 

 function. 



One rat unit as defined in the following chapter corresponds 

 to the hormone content of 10 to 30 grams of whole beef adrenal 

 glands, depending upon the freshness of the glandular material. 

 We thus see that a relatively large amount of glandular ma- 

 terial is necessary for obtaining a sufficient amount of the 

 hormone to be effective therapeutically. 



No valid evidence has been adduced to show that any effects 



