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

  • Lotsy, Johannes Paulus, 1867-1931.
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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    l6 the evolution of living beings. constitute a group of individuals of really identical constitutions. As a matter of fact, one has believed this to be the case for a considerable time. Linnaeus himself thought so, or at least, doubted it only occasionally and then set his doubts aside ; yet he already was convinced himself, that the checking of his conclusions, based on visible differences, necessi¬ tated experiments. Many before him had felt this : John Ray had said already in the 17th Century, that there was no better criterium to distinguish species, than the fact that true species faithfully reproduce their kind by seeds : nulla certior quam distincta propagatio ex semine. This test was frequently, though not under all the necessary precautions, resorted to by Linnaeus who, by applying it, saw that the reproduction was not faithfull, that, on the contrary, the different indivi¬ duals obtained from seeds, supposed to belong to the same species, showed visible differences. Of some of these differences, he could demonstrate the dependency on external conditions and show that they were not transmitted to the offspring, so that they could be neglected. Such differences he called varietates minores, and in order to call the attention of his students to the rela¬ tive unimportance of such differences, he characterised them as: varietates minores non curat botanicus. Unfortunately, Linnaeus drew from a few experiments and observations the conclusion, that all swa//diffe¬ rences between individuals should he considered to be such uninheritable differences, and that consequently