Evolution by means of hybridization / by J.P. Lotsy.

  • Johannes Paulus Lotsy
Date:
1916
Catalogue details

Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: Evolution by means of hybridization / by J.P. Lotsy. Source: Wellcome Collection.

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    8 INTRODUCTION. and this is of so great an importance, because the ne¬ bulae which are considered to be the first stages in the evolution of the celestial bodies consist, if not ex¬ clusively, at least chiefly of Helium. This leads to the conception that during the deve¬ lopment of celestial bodies from nebulae, the elements were formed of HeHum or of a similar substance, and that these elements, later on, united for the greater part with other elements, thus forming more comphca- ted chemical bodies. Bij this process also, water and rocks were formed which, under the influence of the changes in the form of the earth's crust, caused by cooling off, changed places, so that where mountains once were, oceans now spread their waters and reversely. Of course, the time required to bring about all these changes has been a long one ; its length can be deter¬ mined approximately by studying the behaviour of radioactive minerals. Radio-activity namely, proceeds with a velocity, independent of external circumstances such as heat etc., and this allows us to calculate, if the quantity of Helium present in a mineral is known, by determi¬ nation of the quantity of Helium yearly split off by this mineral, the minimum age of it. It was thus possi¬ ble to state positively, that Titanite or Grothitefrom the Archaic Period must, at the very least, be 710 mil¬ lion years of age, and this agrees quite well with the estimate of the earth's age at 1000 millions of years, derived from data, concerning the formation of the great saltbeds.