59 
The most reliable results are obtained by comparing two solutions 
upon eyes from the same frog, thus giving test objects more nearly 
alike, the one solution being used on the right and the other upon the 
left eye. .Although the eyes from other frogs may show for given 
sets a longer or shorter '‘dilation time,” as a rule the higher readings 
will be approximate multiples of the lower, so that the relative values 
of the coefficients of strengths thus obtained will remain about the 
same throughout. 
As indicated in Table XIX the eyes of frogs Xos. 71, 72, and 73 
yield very consistent results. Xot only do the dilation times of the 
weaker solutions agree ^vith each other, but those of the stronger 
agree and the lengths of these times are roughly proportional to the 
concentration. At 18° to 19° C.: 
1:20,000 adrenalin solution causes maximum dilation in 28 to 29 minutes. 
1:40,000 adrenalin solution causes maximum dilation in 27 to 39 minutes. 
1:80,000 adrenalin solution causes maximum dilation in 55 minutes. 
Table XIX. 
Frog X’o. 7 
1. 
Frog Xo. 7 
2. 
Frog Xo. 7 
3. 
Time, i 
Long 
axis. 
Short 
axis. 
Time. 
Long 
axis. 
Short 
axis. 
Time. 
Long : 
axis. ' 
Short 
axis. 
P. m 
M.m. 
M.m. 
P. m. 
il.m. 
M.m. 
P. m. 
M.m. 
M.m. 
Right eve in 1:40,000 
2.52 
3.015 
2.425 
11. 27 
3.250 
2. 550 
1.49 
3. 470 
2.985 
2. 15 
1.916 
1. 305 
10. 48 
1.950 
1.140 1 
1.12 
2.160 ! 
1. 215 
37 min. 
1. 055 
1. 120 
39 min. 
1.300 : 
1.410 
37 min. 
i 1.310 : 
1. 770 
Left eye in 1:20,000 
2.45 
3. 245 
2.985 
11.46 
3.165 
2.715 
2.17 
2.205 
1.480 
11.17 
1.720 ' 
0. 810 
28 min. 
1.040 
1. 505 
29 min. 
1.445 
1.905 : 
Left eye in 1:80,000 
2.4 
3.265 
2. 810 
1.9 
2. 175 
1.135 
1 
1 
55 min. 
1.090 
1.675 
Weight of frogs, Xo. 71=30 grams; Xo. 72=26 grams, Xo. 73=26 grams. 
All the eyes were measured in a Einger-adrenalin solution kept at 18° to 19° C., lighted by a 16- 
candlepower incandescent light under a metaUic reflector. The maximum dilation is determined by the 
time required by first axis to reach its greatest length. 
EELATIVE MYDRIATIC ACTION OF NATURAL L- AND OF SYNTHETIC DL- 
ADRENALIN UPON THE EXCISED FROG’S EYE. 
A comparison of the degree of mydriasis excited by natural 1- and 
synthetic dl-adrenalin seems to indicate that the former is the more 
active. This, however, is not brought out very sharply by comparing 
a large number of eves promiscuous!}'. For example, if the results of 
Tables XYll, XXlil, XXI, XXII, XXIII, and XXIV be compared 
the following relations seem to obtain. 
