78 
lots of animals react very differently to morphine ; thus in our experi- 
ments the fatal dose (by subcutaneous injection) for normal animals 
has ranged from 0.2 to 0.42 mgm. per gram weight for rats,® from 
0.16 to 0.45 mgm. for mice, 6 and from 0.6 to 0.75 mgm. for guinea 
pigs. c We were able to find definite relations between the resist- 
ance of mice to morphine and the diet which they had received; 
whether in addition to this effect of diet the age of the animals, their 
weight or the season, temperature, etc., has an influence we have 
not* been able to definitely determine. Animals which have been 
kept under uniform conditions react very uniformly to the poison, 
and it is possible to determine the fatal dose with great accuracy. 
These experiments afford another illustration of the folly of deter- 
mining the “ fatal dose” of a poison at the beginning of a long series 
of experiments, or, as is often done, accepting such a figure as deter- 
mined by some other investigator and using it as a “control” in a 
new series of experiments. 
a. Experiments on White Rats. 
Series I. 
A. SHEEP THYROID; 0. 176 PER CENT IODINE. 
Date. 
Weight 
of rat. 
Remarks. 
1907. 
May 30 
87 
Feeding of cakes each containing 0.005 gm. thyroid begun. 
June 3 
81 
9 
77 
75 
Morphine sulphate, 2.25 mgms., i. e., 0.03 mgm. per gm. rat. Survived. 
May 30 ! 
88 
Thyroid as above. 
June 3 
84 
7 
79 
9 
' 77 
Morphine sulphate, 3.85 mgms., i. e., 0.05 mgm. per gm. rat. Survived. 
May 30 
107 
Thyroid as above. 
June 3 
98 
7 
94 
9 
92 
Morphine sulphate, 6.44 mgms., i. e., 0.07 mgm. per gm. rat. Survived. 
a T. Sollmann (Textbook of Pharmacology, 2d ed., 1906, p. 954) places the fatal dose of morphine for 
rats at 0.45 mgm. per gram body weight. 
bj. Morgenroth (Berl. klin. Wchnschr., 1903, 49, p. 471) found the fatal dose of morphine hydro- 
chloride for mice in Erankfort on the Main, to be about 0.93 mgm. per gram. 
c T. Sollmann (1. c.) places the fatal dose of morphine for guinea pigs at 0.7 mgm. per gram. 
