Studies in the Theory of Descent: The origin of the markings of caterpillars. 2. On phyletic parallelism in metamorphic species. 3. The transformation of the Mexican axolotl into Amblystoma. 4. On the mechanical conception of natureS. Low, Marston, Searle, & Rivington, 1882 - 729 páginas |
Términos y frases comunes
able according acquired action adaptation adult already alternation appears become brood butterflies caterpillars causes certainly characters climatic cold colour completely conclusion considerably course depend direction distinct Edwards eggs emerged entirely existence experiments explanation exposed extent external eye-spots fact female figured former fourth further genus gradually green hibernate importance individuals influence insects instance Italy June known larva larvæ latter less Levana light male manner Marcellus marking means Napi nature never oblique stripes observed occur origin period phyletic possess possible present primary produced Prorsa pupa pupæ pupal pupation question regarded remain reversion ring-spots seasonal dimorphism secondary segments selection sexual side similar single species specimens stage subdorsal line summer form Telamonides temperature third tion transformation variability variation varieties warmth whilst wings winter form yellow young
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Página vi - maintain with much confidence that organic beings tend to vary and to rise in the scale, independently of the conditions to which they and their progenitors have been exposed; whilst others maintain that all variation is due to such exposure, though the manner in which the environment acts is as yet quite unknown. At the present time there is hardly any question in biology of more importance than this of the nature and causes of variability...
Página 192 - The Natural History of the Rarer Lepidopterous Insects of Georgia, collected from the Observations of John Abbot, with the Plants on which they Feed.
Página 227 - Deilephila hippophaes the ring-like spots of the larva " first originated on the segment bearing the caudal horn, and were then gradually transferred as secondary spots to the preceding segments " (Vol. i, p. 277). Afterwards (1881-1890), Eimet1 showed that in the European wall-lizard " a series of markings pass in succession over the body from behind forwards, just as one wave follows another, and the anterior ones vanish while new ones appear behind.
Página 291 - I watched — at least five minutes — did not return. The larva had been quiet all this time, its tubes out of sight and head buried in a flower bud, but the moment the ant rushed and the fly fled, it seemed to become aware of the danger, and thrashed about the end of its body repeatedly in great alarm. But the tubes were not protruded, as I was clearly able to see with my lens. The ant saved the larva, and it is probable that ichneumons would in no case get an opportunity to sting so long as such...
Página 142 - Of these 9 males, 4 were changed to marcia, var. C, 3 were var. D, and 2 were not changed at all. Of the lo females, 7 were changed, 5 of them to var. B, 3 to var. C. The other 2 females were not different from many tharos of the summer brood, having large discal patches on under side of hind wings, besides the markings common to the summer brood.
Página 290 - Sphinyida; when seized have a habit of doubling up the body and then jumping a considerable distance with a spring-like action. This is especially the case with species having eye-like markings, and it is probable that if attacked by birds in a hesitating manner, such species might effect their escape amid the grass or foliage. Mr. Meldola stated that, in the December number of ' Kosmos,' Fritz Miiller had recorded a number of most interesting observations bearing upon the subject of the coloration...
Página 111 - The general result arrived at by the laborious investigation of these phenomena is, that — " a species is only caused to change through the influence of changing external conditions of life, this change being in a fixed direction which entirely depends on the physical nature of the varying organism, and is different in different species, or even in the two sexes of the same species;" and he adds .-—"According to my view, transmutation by purely internal causes is not to be entertained.
Página 188 - ... existed in those species which fed on low-growing plants, under which conditions the dark colour served as a protection to the caterpillar when hiding by day. Mr. H. Goss said that he had long been familiar with two forms of the larva of Chcerocampa elpenor, and that the green and brown varieties were about equally common, the former colour not being in any way confined to young larvae. Mr.
Página 146 - Nov., 1876, which by his permission I may give in this connection : " Naturally your experiments with tharos have greatly interested me. The case seems to me perfectly intelligible ; marcia is the old, primary form of the species, in the glacial period the only one. Tharos is the secondary form, having arisen in the course of many generations through the gradually working influence of summer heat. In your experiments cold has caused the summer generation to revert to the primary form. The reverting...
Página 127 - Early in the morning I made search for the dead and rejected butterflies, and recovered a few. It was not possible to examine them very closely from the wet and decayed condition they were in, but I was able to discover the broad crimson band which lies above the inner angle of the hind wings, and which is usually lined on its anterior side with white, and is characteristic of either Walshii or telamonides, but is not found in mareellus.