THE ORDER OF DEATH OF ORGANISMS LARGER THAN BACTERIA.

In a previous paper it has been shown that the logarithmic order of death of bacteria can be accounted for by the assumption of some very unstable molecules so essential for reproduction that the inactivation of only one such molecule per cell prevents reproduction and makes the cell appear "dead" according to the standard method of counting living bacteria. In the present paper dealing with the order of death of larger organisms, only a motile alga, Chlamydomonas, is shown to have the same order of death. The very scant material on the order of death of yeasts is contradictory. It seems possible that more than one molecule must be destroyed to kill a yeast cell. With the spores of a mold, Botrytis cinerea, the number of "reacting molecules" is decidedly larger than 1. A flagellate, Colpidium, gave a survivor curve suggesting the destruction of two molecules before motility ceases. Erythrocytes exposed to ultra-violet light also follow the formula for two reacting molecules. The analysis of the survivor curves of multicellular organisms is not possible because no distinction between the number of essential molecules and the number of essential cells seems possible. Besides, variability of resistance changes the shape of the survivor curves in such a way that it becomes impossible to differentiate between variability and actual survivor curve. The general results seem to justify the assumption that in each cell, the number of molecules which are really essential for life and reproduction, is quite limited, and that, therefore, equal cells will not react simultaneously, though ultimately the reaction will be the same. This theory of lack of continuity in cell reactions owing to the limited number of reacting molecules is an analogon to the quantum theory where continuity ceases because division of matter reaches a limit. It seems probable that this lack of continuity in cell reactions has a general biological significance reaching beyond the order of death.