454 



Prof. E. A. Schafer. 



[July 22, 



obvious to the eye between those of the pituitary-fed and control animals. 

 The pituitary -fed rats received with their bread and milk a certain small but 

 constant amount of the dried gland, either from the anterior or from the 

 posterior lobe, the proportion of pituitary substance to the bread and milk 

 food being extremely small. The control animals were fed and kept 

 in a completely similar fashion, except that in place of pituitary an equal 

 amount of the dry powdered substance of some other gland — usually testicle 

 or ovary — was added to the bread and milk. The weight of the animals was 

 regularly recorded. 



Some of the details of one experiment performed in this manner may 

 here be given. A litter of eight rats was taken immediately after being 

 weaned and divided into two groups (A and B) of four each ; the two groups 

 being, as it happened, of exactly the same weight. All were males with the 

 exception of one of the rats of Group B. Both groups were at first put 

 upon the bread and milk diet alone for four days ; it was found that during 

 this period Group B tended to increase in weight slightly faster than 

 Group A. To the diet of Group A was then added a small constant amount 

 of the dry powdered material derived from the anterior lobe of ox 

 pituitaries. Group B, which were kept as controls, received in place of this 

 an approximately equal amount of dried powdered material prepared from 

 the testicle ; for which was, later, substituted a similar material prepared 

 from ovaries.* At an advanced period of the experiment a small amount of 

 powdered material derived from the posterior lobe of the pituitary was 

 mixed with the powdered anterior lobe which was being given to Group A. 

 The experiment was started on March 4 of this year and terminated on 

 June 3. 



At the commencement of the experiment the average weight of each rat 

 was 44 - 25 grammes in each group. A week before the termination of the 

 experiment (i.e. on May 27) one rat of Group A and the female of Group B 

 were killed. At this time the average weight of each rat of Group A was 

 160 grammes ; of each rat of Group B, 131 grammes. After eliminating 

 the female, which weighed only 113 - 5 grammes, and one of the (male) rats of 

 Group A, which weighed 170 grammes, the three remaining (male) animals 

 belonging to Group A were found to average 165 grammes ; while the three 

 remaining (male) animals belonging to Group B averaged 142 grammes. 



At the termination of the experiment the remaining animals, which were 



all healthy, vigorous males, were killed and X-ray photographs were taken of 



them. These have yet to be examined and measured. 



* The amount of calcium in the substances given to the two groups was nearly the 

 same : if anything the balance was against that given to Group A. 



