The American Naturalist, Volumen56Essex Institute, 1922 |
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Términos y frases comunes
A.C. FB adapted alcohol allelomorph animals appear axolotls bacteria behavior Bidder's organ bottle breeding bristles buff canary cells cent changes characters Charles chemical chimæras chromosome coefficient color Columbian controls cross culture Datura Difflugia Drosophila duration eggs environment European goldfinch evidence evolution experimental experiments fact factors females fish flies genes genetic Globe gonad growth guinea pigs heterozygous homozygous hybrids inbreeding individual influence inheritance intersexes Investigations large number larvæ larval linkage litters male mating melanogaster ment Müllerian ducts mutation normal observed occur offspring operculum origin orthogenesis pair parents persistent pigment plants Plethodontida plumage possible present pro-testis probably proboscideans produced progeny proteins ratio rats RAYMOND PEARL reproduction Salamandrida scute self-colored sex-linked similar somatic species Table temperature tests tion tissues triploid variation variegated vertebræ William willistoni wings yellow
Pasajes populares
Página 265 - Papers from the Department of Biometry and Vital Statistics, School of Hygiene and Public Health, Johns Hopkins University, No.
Página 305 - In general there can be no question that this whole matter of influence of density of population, in all senses, upon biological phenomena, deserves a great deal more investigation than it has had. The indications all are that it is the most important and significant element in the biological, as distinguished from the physical, environment of organisms.
Página 44 - It would be very rash to call these bodies genes, and yet at present we must confess that there is no distinction known between the genes and them. Hence we cannot categorically deny that perhaps we may be able to grind genes in a mortar and cook them in a beaker after all. Must we geneticists become bacteriologists, physiological chemists and physicists, simultaneously with being zoologists and botanists? Let us hope so.
Página 33 - ... other, according to their chemical composition. These inorganic forces, according to the newer physics, depend upon the arrangement and mode of motion of the electrons constituting the molecules, which set up electro-magnetic fields of force of specific patterns. To find the principle peculiar to the construction of the force-field pattern of genes would accordingly be requisite for solving the problem of their tremendous auto-attraction. Now, according to Troland (1917), the growth of crystals...
Página 55 - ... genes. We may now reformulate the sex relation as follows: Both sexes are due to the simultaneous action of two opposed sets of genes, one set tending to produce the characters called female and the other to produce the characters called male. These two sets of genes are not equally effective, for in the (chromosome) complement as a whole the female tendency genes outweigh the male and the diploid (or triploid) form is female. The male-tendency genes in the autosomes are more numerous or more...
Página 303 - Comparative Studies on the Effects of Alcohol, Nicotine, Tobacco Smoke, and Caffeine on White Mice. I. Effects on Reproduction and Growth,
Página 55 - When in a diploid zygote the relative effectiveness of the female-tendency genes is lowered by the absence of one X, the male-tendency genes outweigh the female, and the result is the normal male. When the two sets of genes are acting in a ratio between these two extremes, as in the case in the ratio of 2X:3 sets of autosomes (2X:3A), the result is a sex intermediate — the intersex.
Página 98 - Therefore, with due reservations because of the incompleteness of bio-chemical knowledge, it seems reasonable to suppose that apparent instances of orthogenesis may sometimes depend upon a single important chemical change in an organism, followed by slow and progressive modifications leading up to a definitive morphological result.
Página 28 - ... ordinary proteins, carbohydrates, lipoids, and extractives, of their several types, there are present within the cell thousands of distinct substances— the "genes "; these genes exist as ultramicroscopic particles; their influences nevertheless permeate the entire cell, and they play a fundamental role in determining the nature of all cell substances, cell structures, and cell activities. Through these cell effects, in turn, the genes affect the entire organism.
Página 369 - Variations in temperature or in stream flow profoundly influence the reactions and are more powerful factors in the behavior of the fish than presence or absence of salinity.