48 
G. CONTROLS. 
Date. 
Weight of 
mouse. 
Remarks. 
1908. 
June 1 
15.38 
Feeding of cakes without thyroid begun. 
5 
15. 10 
9 
13.92 
Acetonitrile, 2.09 mgms., i. e., 0.15 mgm. per gm. mouse. Survived. 
June 1 
16. 14 
Cakes as above. 
5 
15.42 
9 
15.30 
11 
15.92 
Acetonitrile, 2.55 mgms., i. e., 0.16 mgm. per gm. mouse. Survived. 
June 1 
16.42 
Cakes as above. 
5 
16.86 
9 
15.72 
10 | 
Acetonitrile, 2.67 mgms., i. e., 0.17 mgm. per gm. mouse. Survived. 
June 1 
23. 34 
Cakes as above. 
5 ; 
21.88 
9 
21. 45 
10 
Acetonitrile, 3.86 mgms., i. e., 0.18 mgm. per gm. mouse. Died 1 hour. 
June 1 
17.02 
Cakes as above. 
5 
16.00 
9 
14.78 
10 
Acetonitrile, 2.81 mgms., i. e., 0.19 mgm. per gm. mouse. Died 4§ hours. 
June 1 
18.30 i 
Cakes as above. 
5 
18.42 
9 
17.66 1 
Acetonitrile, 3.53 mgms., i. e., 0.20 mgm. per gm. mouse. Died 1^ hours. 
Summary . — The results of the above experiments may be tabu- 
ated as follows : 
Gm. thy- 
Percentage 
Mgm. I in 
tonitrile in mgm. 
ner em. mouse. 
Thyroid. 
roid fed 
daily. 
of iodine 
in thyroid. 
thyroid 
fed daily. 
Recovered. 
Died, 
A. Alaskan bear 
0. 01 
0 
0 
0. 31 
0.40 
B. Aoudad 
.01 
0 
0 
.22 
C. Black leopard 
.01 
.01 
.001 ! 
. 35 
.40 
D. Cat 
.001 
.08 
.0008 
.70 
.85 
E. Thyraden 
.001 
.085 
.00085 
.76 
.85 
F. Deer 
.001 
.193 
.00193 
1.30 
G. Controls 
.17 
.18 
The thyroid of the Alaskan bear (A) had a low degree of physiolog- 
ical activity. Inasmuch as 0.01 gm. (per cake) protected against 
only about one-half as much acetonitrile as did 0.001 of thyraden 
(0.085 per cent iodine), we may estimate the physiological activity 
of the latter to be approximately twenty times as great at that of the 
former. If the aoudad thyroid (B) had any physiological activity, 
it was too slight to be demonstrated by these experiments; in any 
case, it was distinctly weaker than the Alaskan bear thyroid (A). 
The thyroid of the black leopard (C) with 0.01 per cent iodine was 
apparently no more active than the iodine free thyroid of the Alaskan 
