From 10.47, immediately after the second injection, till 11.20 the average time for clotting was 2.5 minutes, whereas both before and after this period the time was 4 minutes or longer. At 11.00 o’clock and 11.05, when the end point was reached in 1.5 minutes (a reduction of 63 per cent), a thick jelly was found on examining the cannula. The changes in clotting time in this case are represented graphically in [Fig. 26].

Figure 26.—Shortening of coagulation time after injection of adrenin, 0.2 cubic centimeter, 1:100,000, (0.001 milligram per kilo), at 10:46. In this and following Figures a scale for coagulation time is given in minutes at the left.

In another case a dose of 0.0005 milligram per kilo failed to produce any change, but 0.001 milligram per kilo (0.28 cubic centimeter of adrenin, 1:100,000, given a cat weighing 2.8 kilos) brought a sharp decline in the record, as follows:

Jan. 9.11.326minutes
.406“
.47Adrenin, 0.001 milligram per kilo.
.485.5minutes
.554“
12.005.5“
.067“

In these instances the animals were decerebrated. For decerebrate cats, the least amount of adrenin, intravenously, needed to produce shortening of coagulation time is approximately 0.001 milligram per kilo.

In the above cases rapid clotting was manifest directly after minute doses. Larger doses, however, may produce primarily not faster clotting but slower, and that may be followed in turn by a much shorter coagulation time. The figures below present such an instance:

Nov. 25.2.363minutes
.403“
.43 Adrenin, 0.5 cubic centimeter, 1:10,000.
.444minutes
.493.5“
.531.5“
.551.5“
.582“
3.002.5“
.031.5“
.051.5“
.072.5“
.101.5“
.141.5“
.162.5“
.193“
.233“
.303“

This unexpected primary increase of coagulation time, lasting at least six minutes, is in striking contrast to the later remarkable shortening of the process from 3 to an average of 1.7 minutes for more than 20 minutes (see [Fig. 27], A).