30 THE ROYAL SOCIETY OF CANADA 



eighteen days the animals were chloroformed, dissected, and the 

 organs weighed. In the remaining three experiments one or more 

 rats were used as controls (C, in the tables) and fed the bread and 

 milk diet, others were fed this with administration of thyroid ( + r), 

 others fed the vitamin-deficient diet (— F), and others this, plus 

 thyroid in the same ratio ( + T —V). The thyroid was always fed 

 immediately after the animals were weighed in the morning, the dose 

 being based on the body-weight in a constant ratio; it was given 

 mixed with water and flour or oatmeal (according to the diet) to a 

 thin paste, in which form it was always completely eaten. 



Experiment 1. — Seven females of a litter born January 8th, 1921. 

 Treatment commenced on the 80th day of age. On the 98th day 

 the animals were killed and dissected. At autopsy of Rat No. 6 the 

 lymph glands of the throat showed considerable development of pus. 

 This condition has been observed after feeding thyroid, and para- 

 thyroid, and does not, therefore, indicate any special result of the 

 treatment. 



The body- and organ-weights are shown in Table I. 



Experiment 2.- — Eight females of a litter of twelve born September 

 30th, 1920. Treatment commenced on the 70th day of age. On the 

 84th day the animals were killed and dissected. The body- and organ- 

 weights are shown in Table II. 



Experiment 3. — Five male rats of a litter of eleven born February 

 1st, 1921. Treatment commenced on the 39th day of age. On the 

 10th day of treatment the thyroid-fed rat developed typical tetany 

 and died in less than an hour. The others were killed and autopsied. 

 The body- and organ-weights are shown in Table III. 



Experiment 4.- — A litter of four males and five females born 

 January 30th, 1921. Feeding commenced on the 71st day of age. 

 On the 80th day a thyroid-fed female was found dead and the 

 remaining females were killed. The body- and organ -weights are 

 shown in Table IV. The thyroid-fed animal. No. 3, at autopsy 

 showed considerable drying out of surface tissues, and much de- 

 composition within the abdominal cavity. The percentage figures 

 for organ -weights are probably too low. The (-\~T—V) male rat 

 died on the afternoon of the 92nd day (21st of treatment), and the 

 others were immediately killed and autopsied. In these cases the 

 body-weights of that morning (before feeding) were used for calculating 

 the percentage organ-weights. The body- and organ-weights are 

 shown in Table \^ The muscle used for comparison was the right 



