The American Naturalist, Volumen53Essex Institute, 1919 |
Otras ediciones - Ver todas
Términos y frases comunes
adaptive albino aleurone ancestors animals appear Apterygota arthropods aurea average behavior birds blossoms body branchiopods breeding Burley canoe carmine cells cent changes character color cross Crustacea Cumacea Darwin direction Echeneis egg-weight eggs endosperm evidence evolution experiments F₂ fact factors fertilization fish flowers forms gametes Gärtner genetic germ plasm gerrids Gerris remigis habitat heads Hemichordata hens heterozygous homozygous hull-less hulled kernels hybrid individuals inheritance insects intermediate isopods larvæ line of development maize male Mammoth mated means Mendelian ments nature non-yellow normal observed occur offspring Onchidium organism ostrich parent parthenogenetically percentage of hulled pigmentation Pink pink-eyed plants Plecoptera pool present probably produced progeny Protura race ratio regard relation remiges Remora responses seeds segregation selection self-fertilized species sucking-fish surface Symphyla TABLE Tanaidacea temperature tion trilobites turtle variation varieties water-striders yellow Yybb zygospore
Pasajes populares
Página 251 - The next care to be taken, in respect of the senses, is a supplying of their infirmities with instruments, and, as it were, the adding of artificial organs to the natural.
Página 282 - ... than a paltry number of specimens in 1918. The occasion of this sudden and great diminution in the numbers of Sagartia lucice is to be attributed, I believe, to the rigor of the winter of 1917-1918. The cold and ice of this winter were almost unprecedented. Mr. Vinal Edwards, the veteran collector of the laboratory of the United States Bureau of Fisheries at Woods Hole, has kept a continuous record of the weather conditions of this region for a long period and this record shows, as might be expected,...
Página 508 - 04, p. 56) defines the theorem of Le Chatelier as follows : // a system in equilibrium is subjected to a constraint by which the equilibrium is shifted, a reaction takes place which opposes the constraint, ie, one by which its effect is partially annulled.
Página 508 - a system tends to change so as to minimize an external disturbance." The boughs of a tree bend to the wind in proportion to its strength, when the wind is strong...
Página 251 - FIG. 2. comprehend in two general and (unless further explain'd) useless words of Matter and Form. From whence there may arise many admirable advantages, towards the increase of the Operative, and the Mechanick Knowledge, to which this Age seems so much inclined, because we may perhaps be inabled to discern all the secret workings of Nature, almost in the same manner as we do those that are the productions of Art, and are manag'd by Wheels, and Engines, and Springs, that were devised by humane Wit.
Página 555 - Consequently the sexual elements of a hybrid will include both pure and hybridised gemmules ; and when two hybrids pair, the combination of pure gemmules derived from the one hybrid with the pure gemmules of the same parts derived from the other, would necessarily lead to complete reversion of character; and it is, perhaps, not too bold a supposition that unmodified and undeteriorated gemmules of the same nature would be especially apt to combine.
Página 251 - It seems not improbable, but that by these helps the subtilty of the composition of Bodies, the structure of their parts, the various texture of their matter, the instruments and manner of their inward motions, and all the other possible appearances of things, may come to be more fully discovered...
Página 547 - It is interesting to observe in the above several cases the graduated series from plants which, when fertilised by their own pollen, yield the. full number of seeds, but with the seedlings a little dwarfed in stature — to plants which when self-fertilised yield few seeds — to those which yield none, but have their ovaria somewhat developed — and, lastly, to those in which the plant's own pollen and stigma mutually act on one another like poison. It is also interesting to observe on how slight...
Página 544 - ... that it is not the mere crossing of any two individuals which is beneficial to the offspring. The benefit thus derived depends on the plants which are united differing in some manner, and there can hardly be a doubt that it is in the constitution or nature of the sexual elements. Anyhow, it is certain that the differences are not of an external nature, for two plants which resemble each other as closely as the individuals of the same species ever do, profit in the plainest manner when intercrossed,...
Página 256 - Moray propos'da Person that was willing to be entertain'd as a Curator by the Society, offering to furnish them every day when' they met, with three or four considerable Experiments; which Proposition was unanimously receiv'd, Mr. Hooke being nam'd to be the Person ; and accordingly the next Day of their meeting on the twelfth of November he was unanimously accepted and taken as Curator, with the Thanks of the Society order'd to Mr. Boyle for dispensing with him for their i From Hooke 'a diary.