Journal of Morphology, Volumen23Ginn & Company, 1912 |
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adult amphibia Anat animal pole appears Arch artery bilateral Biol blastodisc blastopore body capsules cavity chromatin chromosomes cilia cleavage furrows Clinostomum collecting vessel condition Crepidula Cryptobranchus allegheniensis cuticle cyst cytoplasm degeneration described Desmognathus diameter differentiation disc division dorsal embryo epithelium excretory female fore-gut gastrula germinal vesicle gill groove growth period hours after fertilization hybrids Jour JOURNAL OF MORPHOLOGY larger larvae later layer long axis longitudinal macronucleus male maturation median membrane micromeres Microsauria muscles Necturus neural folds nuclear nuclei nucleoli number of cells observed oesophagus oocyte organs ovarian egg ovary oviduct parenchyma periblast peripheral plana PLATE polar axis posterior protoplasm region relation second polar spindle shown in figure side Spathidium species specimens sperm spermatocyte spermatogonia spermatozoon spherules stages staining structure surface synizesis testis tion urodeles uterus vegetal pole ventral vitelline wall yolk granules zona radiata zone Zool
Pasajes populares
Página 152 - Bull., vol. 3. 1905 The formation of the first polar spindle in the egg of Bufo lentiginosus. Biol. Bull., vol.
Página 68 - ... fine. The boy, in great distress, rushed home to his mother, told his story, and begged her to pay his fine. She, however, promptly recognizing that the whole matter was a joke, refused to pay the supposed fine and, by taking advantage of her son's fear, succeeded in turning him into a model youngster for a period of about two weeks. At the end of this time he discovered that he had been duped and immediately became as mischievous as ever. The dream, as you see, first pictured to the patient...
Página 627 - Heart, blood gland and some of the more important blood vessels. aurl., auricle; gl.sng., blood gland; »., ventricle; va.sng.buc., blood vessel to buccal mass; va.sng.gen., blood vessel to genitalia. The blood gland (fig. 4, gl.sng.) is an irregular leaf-like mass made up of very small round cells. It lies immediately above the central nervous system and has an antero-posterior diameter of 7 mm. and a lateral diameter of 5 mm. NERVOUS SYSTEM The nervous system consists of two main divisions —...
Página 72 - As a result of experimental studies on the nature of the stimulus which causes the shell to be formed about .the hen's egg, Pearl ('09) reached the following conclusions: (a) the stimulus which sets the shell-secreting glands of the fowl's oviduct into activity is mechanical rather than chemical in its nature; (b) the formation of a shell on the hen's egg is brought about by a strictly local reflex, and is not immediately dependent upon the activity of other portions of the reproductive system (nervous...
Página 262 - The nodes vary considerably in arrangement not only in different specimens but in different parts of the same specimen.
Página 453 - XII. 1889. The Morphology of the Carotids, based on a study of the Blood Vessels of Chlamydoselachus anguineus.
Página 310 - the polar axis persists unmodified from generation to generation in the vertebrates and is one of the fundamental features of the organization of the protoplasm" (p. 310). Furthermore, experiments with centrifuged force seem to prove that the chief axis of the egg is not altered when substances are shifted about, but is fixed at all stages (Lillie, '09; Morgan, '09; Conklin, '10). Bilaterality also is demonstrable in the early stages of the germ cells of...
Página 183 - It is notable that the number of capsules formed is nearly the same in the two varieties, though there is a great difference in the number of eggs inclosed in each capsule. In Crepidula, therefore, the cell size is...
Página 161 - He says (p. 543): In 0. gigas we have an organism built of bricks which are larger and whose relative dimensions are also altered in some cases. These two factors will apparently account for all the differences between 0. gigas and 0. lamarckiana, and the second factor may be one merely of readjustment consequent upon the first.
Página 181 - ... shaped so as to fit the surface upon which they had found a new home. In every such shell one can recognize both the dwarf and the normal forms. The dwarfs are what they are by reason of external conditions, and not because of inheritance; they are, in short, a physiological and not a morphological variety.