43 
The iodine free thyroid of the Alaskan bear (A) had some physio- 
logical activity, but it was much (perhaps about seven times) less 
than that of Thyraden (D), with 0.085 per cent iodine. The iodine 
free thyroid of the aoudad (B) was evidently less active than that of 
the Alaskan bear; in fact, there is nothing in this series to indicate 
that it had any activity whatever, but perhaps the doses of acetonitrile 
were too large. A point of interest is the fact that the thyroid of the 
black leopard (C), which contained 0.01 per cent iodine, was certainly 
not more active than the “ iodine free” thyroid of the Alaskan bear. 
Of course it is possible that there was a small amount of iodine in the 
latter which was overlooked in the analysis; unless this is the case 
(and the probabilities are that it is not) we must conclude that at 
times iodine free thyroid is as active as thyroid containing a mini- 
mum amount of iodine. 
Series VI. 
A. THYROID OF MALTESE KID; IODINE FREE. 
Date. 
Weight 
of mouse. 
Remarks. 
1908. 
September 5. . . 
17.60 
Feeding of cakes each containing 0.01 gm. thyroid commenced. 
9... 
17.24 
12... 
16.90 
14... 
16.02 
Acetonitrile, 4 mgms.. i. e., 0.25 mgm. per gm. mouse. Survived. 
September 5. . . 
18.76 
Thyroid as above. 
9... 
18.02 
12... 
17.72 
14... 
17.13 
Acetonitrile, 4.62 mgms., i. e., 0.27 mgm. per gm. mouse. Died 2 hours. 
September 5... 
18. 75 
Thyroid as above. 
9... 
19. 70 
12... 
19.54 
13... 
Acetonitrile, 5.86 mgms., i. e., 0.3 mgm. per gm. mouse. Died 2 \ hours. 
September 5... 
19.40 
Thyroid as above. 
9... 
17.30 
12... 
17.04 
13... 
Acetonitrile, 7.67 mgms., i. e., 0.45 mgm. per gm. mouse. Died H hours. 
B. THYROID OF ALASKAN BEAR: IODINE FREE. 
1908. 
September 5... 
17.40 
Feeding of cakes each containing 0.01 gm. thyroid commenced. 
9... 
17.82 
12... 
18.88 
14... 
19.02 
Acetonitrile, 8.56 mgms., i. e., 0.45 mgm. per gm. mouse. Survived. 
September 5... 
15.24 
Thyroid as above. 
9... 
14.46 
12... 
14 80 
13... 
Acetonitrile, 7.4 mgms., i. e., 0.5 mgm. per gm. mouse. Survived. 
Thyroid as above. 
September 5... 
20.24 
9... 
20.08 
12... 
19.28 
14... 
18. 94 
Acetonitrile, 10.04 mgms., i. e., 0.53 mgm. per gm. mouse. Died 1J hours. 
September 5... 
19.00 
Thyroid as above. 
9... 
18.76 
12... 
18.00 
13... 

1 Acetonitrile, 10.8 mgms., i. e., 0.6 mgm. per gm. mouse. Died 3 hours. 
