This assumption is undoubtedly correct.

We will, in the first instance, make a rough calcula­tion of what would happen if such an organism were detached from the earth and pushed out into space by the radia­tion pressure of our sun. The organism would first of all have to cross the orbit of Mars; then the orbits of the smaller and of the outer planets. . . . The organisms would cross the orbit of Mars after twenty days, the Jupiter orbit after eighty days, and the orbit of Neptune after fourteen months. Our nearest solar system would be reached in nine thousand years.

For the assump­tion of eternity of life only the transference of germs from one solar system to another would have to be considered and the ques­tion arises whether or not germs can keep their vitality so many thousands of years. Arrhenius thinks that this is possible on account of the low temperature (which must be below -220° C.) at which no chemical reac­tion and hence no decomposi­tion and deteriora­tion are possible in the spores; and on account of the absence of water vapour.

The ques­tion then arises: Have we any facts to warrant the assump­tion that spores may remain alive for thousands of years under such condi­tions and retain their power of germina­tion? We know that seeds have a very limited vitality, and the statement that grain found in the Egyptian tombs was still able to germinate has long been recognized as a myth. Miss White[27] found that in wheat grains, there appeared a well-marked drop in their germinating power after about the fourth year, reaching zero in eleven to seventeen years. In a drier climate they last longer than in a moist climate. It is of importance that the hydrolyzing enzymes in the seeds, such as diastase, erepsin, remained unimpaired even after the germinating power of the seeds had disappeared. The seeds were able to resist for two days the temperature of liquid air, though the subsequent germina­tion was delayed by this treatment. Macfadyen[28] exposed non-sporing bacteria, viz., B. typhosus, B. coli communis, Staphylococcus pyogenes aureus, and a Saccharomyces to liquid air.

The experi­ments showed that a prolonged exposure of six months to a temperature of about -190° has no appreciable effect on the vitality of micro-organisms. To judge by the results there appeared no reason to doubt that the experi­ment might have been successfully prolonged for a still longer period.

Paul Becquerel[29] found that seeds which possess a very thick integument may live longer than the grain in Miss White’s experi­ments. The thickness of the integument prevents the exchange of gases between air and seed. Thus seeds of leguminoses (Cassia bicapsularis, Cytisus biflorus, Leucæna leucocephala, and Trifolium arvense) had retained their power of germina­tion for eighty-seven years. Becquerel has shown that the dryness of the membrane is very essential for such a dura­tion of life, since when dry it is impermeable for gases and the slow chemical reac­tions inside the grain become impossible.

In the cosmic space there is no water vapour, no atmosphere, and a low temperature, and there is hence no reason why spores should lose appreciably more of their germinating power in ten thousand years than in six months. We must therefore admit the possibility that spores may move for an almost infinite length of time through cosmic space and yet be ready for germina­tion when they fall upon a planet in which all the condi­tions for germina­tion and development exist, e. g., water, proper temperature, and the right nutritive substances dissolved in the water (inclusive of free oxygen).

While thus everything is favourable to Arrhenius’s hypothesis, Becquerel raises the objec­tion that the spores going through space would yet be destroyed by ultraviolet light. This danger would probably exist only as long as the germ is not too far from a sun. The difficulty is a real one since the ultraviolet rays have a destructive effect even in the absence of oxygen. It is possible, however, that there are spores which can resist this effect of ultraviolet light. Arrhenius’s theory can not of course be disproved and we must agree with him that it is consistent not only with the theories of cosmogony but also with the seeming potential immortality of certain or of all cells.

The alternative to Arrhenius’s theory is that living matter did originate and still originates from non-living matter. If this idea is correct it should one day be possible to discover synthetic enzymes which are capable of forming molecules of their own kind from a simple nutritive solu­tion. With such synthetic enzymes as a starting point the task might be undertaken of creating cells capable of growth and cell division, at least in the apparently simple form in which these phenomena occur in bacteria; viz., that after the mass has reached a certain (still microscopic) size it divides into two cells and so on. If Arrhenius is right that living matter has had no more beginning than matter in general, this hope of making living matter artificially appears at present as futile as the hope of making molecules out of electrons.

The problem of making living matter artificially has been compared to that of constructing a perpetuum mobile; this comparison is, however, not correct. The idea of a perpetuum mobile contradicts the first law of thermodynamics, while the making of living matter may be impossible though contradicting no natural law.