Since this was written, two more of the parthenogenetic frogs over a year old died.
Delage[113] was courageous enough to make an attempt to raiseparthenogenetic larvae of the sea urchin beyond the larval stage and he succeeded in one case in carrying the animal to the mature stage.
Bancroft and the writer tried to determine the sex of a parthenogenetic tadpole and of a frog just carried through metamorphosis.
In the latter case a purely parthenogenetic mode of propagation is observed, while in the former sexual reproduction takes place.
The writer has recently examined the gonads of a ten months old parthenogenetic frog.
It has been shown for certain cases, and it may be true generally, that if eggs of this type give rise to parthenogenetic females they may do so because they have for some reason two X chromosomes.
When the sperm is added while the eggs are in active parthenogenetic cell division the individual blastomeres into which a spermatozoon enters will also form a fertilization membrane, but such blastomeres perish very rapidly.
He has at present sevenparthenogenetic frogs over a year old, produced by merely puncturing the eggs with a fine needle (Fig.
In certain forms parthenogenetic and sexual reproduction may alternate in a cycle, e.
Heterogeny: the alternation of sexual and parthenogenetic generations.
Deuterotoky: parthenogenetic reproduction when the progeny are male and female: see arrhenotoky and thelyotoky.
Heterogamy: applied to those cases in which two sexual or a sexual andparthenogenetic generation alternate.
But, as we have seen, this is sometimes the case in eggs which are fertilized, and parthenogenetic ova are known which form two polar bodies, e.
For instance, it has been said thatparthenogenetic ova form only one polar body.
The extrusion of polar bodies is probably universal among animals, but only one polar body is extruded from parthenogenetic ova.
The last line of direct evidence, or that derived from the alleged non-variability of parthenogenetic organisms, is, as Professor Vines has shown, opposed to fact.
Secondly, Weismann says that in parthenogenetic ova only one polar body is extruded.
The parthenogenetic birth of Christ, simple enough at first as a popular miracle, was not left so simple by the theologians.
In the thirdparthenogenetic generation not a single egg yielded a caterpillar.
With most of the lower animals and even with mammals, the ova show a trace of parthenogenetic power, for without being fertilised they pass through the first stages of segmentation.
A female insect producing eggs from which young are hatched, though there has been no fecundation by a male; a parthenogenetic insect.
In many insects and other Arthropods which are not parthenogenetic the male has been found to possess fewer chromosomes than the female.
The chief difference in this case then is that the reduction in the male to the N or simplex condition takes place in two stages, one in the parthenogenetic ovum, one in the gametes of the mature male.
The parthenogenetic ovum of the bee is male, and yet it is an ovum capable only of producing spermatozoa.
Terry had insisted that if they were parthenogenetic they'd be as alike as so many ants or aphids; he urged their visible differences as proof that there must be men--somewhere.
Defn: A female insect producing eggs from which young are hatched, though there has been no fecundation by a male; a parthenogenetic insect.
In addition to these parthenogenetic eggs, which hatch at once while still within the brood-chamber, the Cladocera produce, at certain seasons, another kind of egg which requires to be fertilized by the male before it will develop.
The parthenogenetic eggs, as in other Cladocera, develop directly, but the resting eggs give rise to larvae of the nauplius type.
In certain gall-flies (Cynipidae) no males are known to exist at all, and the species seems to be preserved entirely by successive parthenogenetic generations.
Among the vertebrata parthenogeneticdevelopment has also been observed, though rarely reaching maturity.
As a rule theparthenogenetic offspring are themselves incapable of further procreating their kind.
BR] One parthenogenetic form--the drone--has been shown by Blochmann to extrude a second polar cell.
As this sheet is passing through the press Agar has published[6] an abstract of evidence as to another comparable case in a parthenogenetic strain in the daphnid, Simocephalus vetulus.
Even theparthenogenetic baby girls born as a result of the unfortunate experiment of the Venusians were white.
The remarkable observations of Professor Greeff (19) on the parthenogenetic development of the eggs of Asterias rubens tell, however, very strongly against this explanation.
The militia are under arms, as riots are expected.
The violent shock has been communicated, like that of electricity, through the country to a distance of hundreds of miles.
Not a smile on one countenance among the crowd who pass and repass; hurried steps, careworn faces, rapid exchanges of salutation, or hasty communication of anticipated ruin before the sun goes down.
In the hatter's shop, to be sure," rejoined the fox, tripping lightly away.
We embarked again, and after an hour's paddling landed upon a small island, where was the tomb of an Indian chief or warrior.
I walked down Wall Street, and had a convincing proof of the great demand for money, for somebody picked my pocket.
Suspicion, fear, and misfortune have taken possession of the city.
Affairs are now at their worst, and now that such is the case, the New Yorkers appear to recover their spirits.
My appearance at New York was very much like bursting into a friend's house with a merry face when there is a death in it--with the sudden change from levity to condolence.
We threw off our clothes, and plunged into the lake; the water was too cold; the agates at the bottom cut our feet severely, and thus were we phlebotomised from head to foot.
Poulton suggests one, in the fact that parthenogenetic reproduction only occurs in isolated species, not in groups of related species; as this shows that parthenogenesis cannot lead to the evolution of new forms.
Again, in parthenogenetic females the complete apparatus for fertilisation remains unreduced; but if these varied as do sexually produced animals, the organs referred to, being unused, would become rudimentary.
Probably the parthenogenetic strain was the form involved in most Pacific areas.
The parthenogenetic strain is undoubtedly the form that has been shown to be the host of O.
Study of the bisexual and parthenogenetic strains of Pycnoscelus surinamensis (Blattaria: Epilamprinae).
The question of dominance is a difficult one, especially in parthenogenetic eggs and eggs which are distinctly male or female before fertilization.
Coupling is not fecundation; it is merely the mechanism; its utility is merely in that it puts two parthenogenetic products into relation.
Footnote 2: The back as gestative chamber is also found in woodlice, during one of their parthenogenetic phases, cf.
The parthenogenetic female lives for hardly a day, and the same is true of the parthenogenetic females of another species of Solenobia’ (S.
If it were physiologically valueless, such a phyletic reminiscence of the two successive divisions of the egg-nucleus must have been also retained by the parthenogenetic egg.
Footnote 156: The formation of a polar body in parthenogenetic eggs has now been proved: see note at the end of this Essay; see also Essay VI.
This form of parthenogenetic reproduction is especially well suited to the needs of species inhabiting small pools which entirely depend upon rain-fall, and which may disappear at any time.
The question which I have raised on a previous occasion—‘When is the parthenogenetic egg capable of development?
In many other Daphnidae which have come under my notice, the females frequently enter again upon the formation of parthenogenetic summer-eggs, after having laid fertilized resting eggs, upon one or more occasions.
The case is quite different in species which retain both sexual and parthenogenetic reproduction.
The transition from sexual to parthenogenetic reproduction only occurs in one species of Moina (M.
If we wish to form a mental image of the process of evolution we have to reckon with the possibility that parthenogenetic propagation may have preceded sexual reproduction.
How the males are formed--for of course males are eventually produced by the parthenogenetic females--we do not know.
Eggs capable of parthenogenetic development, produced in large numbers in the ovaries of these females, give rise to young which, developing within the body of the mother, are born in an active state.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "parthenogenetic" in a variety of sentences. We hope that you will now be able to make sentences using this word. Other words: generative; genetic; genial; genital
