Mayer's Ontogeny and phylogeny of insects.

  • Packard, A. S. (Alpheus Spring), 1839-1905.
Date:
[1876?]
Catalogue details

Licence: Public Domain Mark

Credit: Mayer's Ontogeny and phylogeny of insects. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    > t a MAYER’S ONTOGENY AND PHYLOGENY OF INSECTS.1 “ Ontogeny ” is a term devised by Haeckel, and means the develop- ment or embryonic and post-embryonic changes of the individual; “ phy- logeny ” corresponds to its English equivalent, “ancestry,” while the present essay is an attempt to explain the origin and ancestry of the six- footed insects (Hexapoda) from embryological and anatomical data. No new facts, so far as we are aware, are presented by the author, whose essay has, apparently, contrary to usage in German universities, been crowned not for the original work it contains but for the ideas suggested by the labors of preceding authors. In trying to reconstruct the form of the primitive insect, Mayer in- sists that it should be done from a study of the winged adult or imago, “since a priori we cannot know how far the form of the larva is original or secondary.” Other authors have with better reasons derived the an- cestral form from the larva. Mayer’s ancestral insect, then, which he calls Protentomon, had a body divided into a head, thorax, and abdomen, the latter consisting of eleven segments, while there were six thoracic feet with five-jointed tarsi, and two pairs of wings, nine (and perhaps eleven) pairs of stigmata, a pair of salivary glands, and four excretory organs or Malpighian vessels, be- sides a well-developed nervous system, heart, and an aorta, as usual in existing insects. This hypothetical Protentomon is derived by Mayer from the worms,2 in opposition to the suggestions of Fritz Muller and Brauer that the insects originated from the Crustacea. This worm (1), the parent of the half a million species of insects which have peopled the globe during the present and past ages, was “ an unjointed worm, a common st ^ting-point for the Tracheata and higher worms, and also a near relation of the ancestral form of the Crustacea.” This worm then (2) transformed into a higher organism, with eighteen joints to its body and at least fourteen pairs of segmental organs, with perhaps also a masti- catory apparatus in the form of jaws ; and was perhaps nearly related to 1 Ueber Ontogenie und Phylogenie der Insekten. Eine akadcmische Preisschrift. Von Dr. Paul Mayer, in Jena. Jenaische Zeitschrift fur Naturwissenschaft., x., heft 2. Jena. 1876. With four plates, pp. 125-221. 2 This view was advocated by the writer (though Mayer does not mention it) in Our Common Insects, chapter xiii., entitled Ancestry of Insects (1873). This is the more inexcusable since Dr. Mayer quotes from the essay.