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Percentage of Nitrogen in the Solids

body-weight, cassiopea, starved, mayer and grams

PERCENTAGE OF NITROGEN IN THE SOLIDS.

As in the case of the normal cassiopea, the nitrogen-content is highest in the smaller animals and tends to decrease with increasing body weight. The value of the nitrogen is, however, much higher in the starved cassiopea than in the normal cassiopea of similar body-weight (see table 7).

Thus, 5.56 grams of the normal series gives 2.98 per cent of nitrogen contrasted with 3.63 per cent of nitrogen in the starved cassiopea having a body-weight of 5.83 grams. Such a relation is clearly shown in the majority of cases. It is highly interesting to observe that the percentage of nitrogen is notably high for the final starved body-weight when com pared with that in the control with a similar body-weight (table 7), but it is much lower for the initial unstarved body-weight, as will be seen from the extremely low percentage of nitrogen when calculation was made in respect to the initial body-weight instead of the final (see table 7, sixth column). This indicates clearly that during starvation the animal has utilized a considerable amount of the nitrogenous substances—a conclu sion which is important, as it answers the main question before us and brings Cassiopea in line with the vertebrates in its reaction to starvation conditions. It is highly probable that some fraction of the nitrogen uti lized may represent that of the cellular substance. Mayer (1914) noted, from the sections made on the starved cassiopea, not only reduced cell size, but also many degenerated cell-bodies, and there was evidence also of a complete disappearance of some of the cellular elements. Mayer found also a vacuolated condition of the gelatinous substance accom panied by a greater loss of the muscular tonus. The chemical altera

tions noted above accord with his findings.

Mayer concluded that the percentage of nitrogen in the solids is independent of the period of starvation and is practically identical with that obtained from the non-starved cassiopea. I have, however, found, as stated above, that starvation tends to increase not only the percentage of nitrogen in the solids, but also that the absolute amount of nitrogen shows an increase when the starved cassiopeas were com pared with the normals having the same body-weight. The discrep ancy between the conclusions drawn by Mayer and by myself is, I believe, due to the fact that Mayer's observations were limited to the larger cassiopeas (body-weights over 100 grams) in which the percent age of nitrogen in the solids shows little variation following the large variations of the body-weight, while the variations in the nitrogen are quite noticeable in the cassiopeas of smaller size. I may add here that the data given by Mayer' show also a slight indication of a difference in the nitrogen-content between the normal and starved cassiopeas; thus the nitrogen-content in the normal is 2.35 per cent for a body weight of 109.3 grams, while the starved gives 2.47 per cent of nitrogen for a final body-weight of 92.4 grams. These differences agree with my own findings.

I am thus inclined to believe that even these larger cassiopeas may show a significant degree of alteration after a longer period of starva tion than that given them by Mayer, and when the animals have lost 80 per cent or so of their initial body-weight.