The much more extensive literature dealing with inanition in verte brates shows that the loss of body-substance takes place in a highly selective manner, involving many tissues before any marked loss is undergone by the " vital organs." Several researches in this field have demonstrated the importance of metabolic muscular activity as a factor in determining the rate of tissue destruction. The usual course of the changes involved in inanition is not, however, greatly altered by differences in the rate of metabolism, the one factor most influenced being the rate of occurrence of these changes.
The results of three series of experiments, in each of which the halves of 20 disks were prepared in such a manner that they fell into one of the three categories described on pages 127 and 128, are presented in tables 6, 7, and 8, and figures 10, 11, and 12.
A summary of the results for each of the series of experiments is given in their proper order in table 9, in which the weights are reduced to terms of 100 grams for the original weight of each set of half-disks in each series. A comparison of these tables and the curves for the loss of weight with those given for the rates of regeneration under similar operations show a striking similarity in the results when thosv obtained by the use of these standards of measurement are compared, although, as previously stated, the tissues chiefly concerned in the two forms of metabolic activity are fundamentally different.
Table 10 gives the record of the halves of 10 disks prepared to give active and inactive specimens and shows loss in weight, decrease in diameter, measured for each half-disk at the line of separation of the halves, and shrinkage in the diameter of a cavity originally 22 mm. In several instances the diameters of the halves of the same disk vary 1 to 3 mm. on account of irregularities in the outline due to the cuts made in removing the sense-organs or the similAr-shaped pieces of tissue between the sense-organs of the active half-disk.
The results of the measurements of size are completely in accord with those obtained in studying the loss in weight of the same half-disks, or the larger series of specimens prepared in the same manner, as shown in table 6. Although in the greater number of regeneration experiments no careful measurements were made of the decrease in the diameter of the cavity in which the amount of regeneration was measured, the differences in this regard between the different types of specimens was easily distinguishable in all cases and was always parallel to the relative rate of regeneration shown by either one of a given pair of half disks, by whichever of the three operations they had been prepared.