SCIENTIFIC AMERICAN SUPPLEMENT Nn 2208 267 Butschli, Hertwig, and others, the sole remedy against senile degeneracy and natural death 7" After Enriques, Brown (for the Spirogyrre) ," Wood ruff and S. Metalvikoff13 (for the Infusorre) have shown that the lower organisms can produce themselves indef initely without conjugation and that, in a favorable location, they are immortal. It is, perhaps, only unfavorable conditions, and the approach of death, which cause sexual reproduction to make its

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... earance." Fecundation, moreover, is nothing but a chemical effect resulting from the action of oxygen, or of cer tain ions," on the substances in the ovule to make them soluble. Sexual rejuvenation is a very different phenomenon. ,. It is, above all, the period of repose, the cyst or spore phase of the Thallophytes, the macrospore phase" of the vascular Cryptogams, the seed phase of the Phan erogams, the 1vinter repose'" of perennial plants of tem perate countries. the repose of the Mesophytes of the desert during the dry season,'·-it is latent Ufe which characterizes rejuvenation in general."· The passage from latent life to active life cannot take place without excitation. F. W. Covelle has just shown this for the buds of whortleberry Myrtille (Vac cinium), which, when it is not exposed to the frosts of winter, does not transform its amylaceous reserves into sugar, and does not develop in the spring.81 Heat and humidity suffice to release the development of the majority of seeds or winter ·buds." However, the seeds of the Orchidaceae" and of the Ericaceae S4_S6 (heather, arbute berryS6) ill order to germ inate must be excited by symbiotic fungi, and the same phenomenon is perhaps very general (hard seeds).