The Shipley Collection of Scientific Papers, Volumen231897 |
Dentro del libro
Resultados 1-5 de 38
Página 8
... granules of black pigment ( Fig . 3 , F ) , by means of which they are so unmistakably marked that their later his- tory may be followed step by step with great accuracy . Thus arises the pigment - area at the lower pole of the ...
... granules of black pigment ( Fig . 3 , F ) , by means of which they are so unmistakably marked that their later his- tory may be followed step by step with great accuracy . Thus arises the pigment - area at the lower pole of the ...
Página 9
... granules are found throughout the whole thick- ness of the wall ( Fig . 4 , B ) . The pigment - cells are , therefore , not mesoblastic , but are entoblast - cells . In so far as the pigment - cells are derived from the macro- meres ...
... granules are found throughout the whole thick- ness of the wall ( Fig . 4 , B ) . The pigment - cells are , therefore , not mesoblastic , but are entoblast - cells . In so far as the pigment - cells are derived from the macro- meres ...
Página 18
... granular cells ( Fig . 6 , F ) which may easily . be seen for a long time through the transparent ectoblast and from which the greater part , if not all , of the adult mesoblast is derived . It is clear from these facts that the cells ...
... granular cells ( Fig . 6 , F ) which may easily . be seen for a long time through the transparent ectoblast and from which the greater part , if not all , of the adult mesoblast is derived . It is clear from these facts that the cells ...
Página 20
... granular cells conspicuously seen through the trans- parent outer cells . A study of the successive stages proves that the greater number of these are derivatives of the second quartet ; but the possibility remains that some additions ...
... granular cells conspicuously seen through the trans- parent outer cells . A study of the successive stages proves that the greater number of these are derivatives of the second quartet ; but the possibility remains that some additions ...
Página 27
... granules group themselves into 24 chromo- These 24 chromosomes become arranged in pairs , the indivi- dual chromosomes of each pair being connected with each other by a considerable number of linin threads . Later the pairs become asso ...
... granules group themselves into 24 chromo- These 24 chromosomes become arranged in pairs , the indivi- dual chromosomes of each pair being connected with each other by a considerable number of linin threads . Later the pairs become asso ...
Términos y frases comunes
American eggs Amphioxus animals annelids appear Appendicularia archenteron Aricia arrangement autotomy axis-cylinder process bones buds cave-earth cavern cell body cell of Helix cell-lineage cells of Invertebrates cellular centrosomes character chromophilous chromophilous granules chromosomes colonial condition curve density depth determined differentiation direction disease distilled water division ecdysis embryo entoblastic evidence existence fact fathoms fibrils FLEMMING'S foliage-leaves function ganglion cells gasteropods geological germ-plasm give granular rows ground-substance growth haematoxylin Heredity hydrometer individual investigation large number latter leaves Leptoplana mesoblast-bands mesoblasts metamorphosis method methylen blue morphological Museum naturalists Nereis nerve cells neuroglia neuroglia fibrils nucleus observations ocean offspring organs origin plant plate polyclade position posterior present primary mesoblasts produce quartet regard reproductive cells safranin segmentation segmentation nucleus slug solution species specimens spindles spiral sporophyll stained stalagmite stem structure substance surface tarsus temperature theory tion tissues variations Vertebrates
Pasajes populares
Página 7 - I happened to read for amusement 'Malthus on Population', and being well prepared to appreciate the struggle for existence which everywhere goes on from long-continued observation of the habits of animals and plants, it at once struck me that under these circumstances favourable variations would tend to be preserved, and unfavourable ones to be destroyed. The result of this would be the formation of new species. Here then I had at last got a theory by which to work...
Página 2 - And pretty dwarfs to show the way Through fairy hills and fairy dales. But when a bad child goes to bed, From left to right she weaves her rings, And then it dreams all through the night Of only ugly horrid things ! Then lions come with glaring eyes, And tigers growl, a dreadful noise, And ogres draw their cruel knives, To shed the blood of girls and boys.
Página 2 - LITTLE fairy comes at night, Her eyes are blue, her hair is brown, With silver spots upon her wings, And from the moon she flutters down. She has a little silver wand, And when a good child goes to bed She waves her wand from right to left, And makes a circle round its head.
Página 11 - human remains and works of art, such as arrow-heads and knives of flint, occur in all parts of the cave and throughout the entire thickness of the clay : and no distinction founded on condition, distribution, or relative position, can be observed, whereby the human can be separated from the •other reliquiae," which included bones of the "elephant, rhinoceros, ox, deer, horse, bear, hyaena, and a feline animal of large size.
Página 4 - Les noms géographiques des nations qui emploient, dans leur écriture, des caractères latins (langues néo-latines, germaniques, Scandinaves), seront écrits avec l'orthographe de leur pays d'origine. Les règles qui vont suivre s'appliquent uniquement aux noms géographiques de pays qui n'ont point d'écriture propre ou qui écrivent avec des caractères différents des caractères latins. Toutefois, à titre exceptionnel, on conservera l'orthographe usitée pour les noms de lieux, lorsqu'elle...
Página 8 - It may well be doubted ; and yet one is always the better for a walk in the morning air, — a medicine which may be taken over and over again without any sense of sameness, or any failure of its invigorating quality.
Página 12 - Whatever other causes have been at work, natural selection is supreme, to an extent which even Darwin himself hesitated to claim for it. The more we study it the more we are convinced of its overpowering importance, and the more confidently we claim, in Darwin's own words, that it ' has been the most important, but not the exclusive, means of modification...