Precipitation Tests in Mice: III. A Disturbance between Two Hundred and Three Hundred Days of Life

Abstract

In the first and second papers of this series 2 data were presented which indicated that there was, with advancing age, a gradually decreasing amount of a trichloracetic acid-total blood precipitate in individuals of the inbred A strain of mice. These data are further analyzed here.

Chart 1 presents the data obtained on normal females of the A strain, classified (1) according to age and (2) according to hours of deprivation of food. The latter classification is given along the base line, the reading of the precipitate along the ordinate. The data for the mice between 101 and 200 days of life are represented by the solid line; for mice between 201 and 300 days by the short dash line; for mice between 301 and 400 days by the dotted line; for mice between 401 and 500 days by the long dash line; and finally for mice between 501 and 600 days of life by the dot and dash line. Each point on the chart was determined by the average of several independent observations; the individual determinations in each point are given in the small numeral adjacent to that point.

It will be noted that three of the curves are very close together, namely those for the mice from 101 to 200 days old, from 301 to 400 days old, and from 401 to 500 days old. Because of the proximity of these three curves, they were combined and appear as a single curve in Chart 2.

For the sake of discussion, it may be assumed that there are two fundamental types of curve. The first type (a) was obtained in young animals between 101 and 200 days of life. This type of curve was found, also, in mice between 301 and 600 days of life. Since the curve encountered in mice of 101 to 200, and 301 to 500 days of life and that for mice of 501 to 600 days are practically parallel, one may conclude that the only difference here is due to the absolute reading. The second type of curve (b) is that for mice between 201 and 300 days of life.

There is thus indicated a disturbance in mice in the mechanism or mechanisms that control the final precipitate reading between the ages of 201 and 300 days of life. It is of interest to bring this finding into relation with the mortality curve for individuals of the same strain.