Rouen breed, which is stronglydimorphic in plumage.
Even more remarkable is the fact that in some sexually dimorphic species a change of temperature alters the female, so as to cause her to have the outward appearance of the male.
On this hypothesis the females are supposed to be able to pick and choose their mates, and to select the most beautiful and ornamental ones, hence the greater showiness of these in most sexually dimorphic species.
Similar results have been obtained with the seasonally dimorphic Pieris napi.
The Arctic fox appears in all three columns, as the creature seems to fall into three races--a permanently white race, a permanently coloured race, and a seasonally dimorphic race.
We have already cited the case of the curious sexually dimorphic red turtle-dove.
It is worthy of notice that the various features which characterise the sexes in sexually dimorphic animals are not associated with any particular organ or parts of the body, nor do they necessarily affect the same part in allied species.
Standfuss, the Graefin von Linden, and others have obtained like results in the case of other seasonallydimorphic butterflies.
I ought to have written before to thank you for the copies of your papers on Primula and on "Cross-unions of Dimorphic Plants, etc.
By the way, my notions on hybridity are becoming considerably altered by my dimorphic work.
Asa Gray and Fritz Muller (the latter especially) think that the new facts on illegitimate offspring of dimorphic plants, throw much indirect light on the subject.
The Indian redstart is a sexuallydimorphic species, that is to say the cock differs from the hen in appearance; the former, moreover, is seasonally dimorphic.
Some entomologists have thought them simply varieties or dimorphic forms while others have considered them hybrids.
As is the case with so many other butterflies there is a dimorphic form, called ocellata, in which the outer half of the hind wing is very dark brown, with the eye-spot showing as black with red-brown circles.
Fritz Muller has described a remarkable dimorphic species of Tanais, in which the male is represented by two distinct forms, which never graduate into each other.
Canestrini draws the same conclusion from the fact that the males of certain species present two forms, differing from each other in the size and length of their jaws; and this reminds us of the above cases of dimorphic crustaceans.
Tanais, absence of mouth in the males of some species of; relations of the sexes in; dimorphic males of a species of.
This latter hypothesis was readily confuted by the fact, that the most strongly marked of the dimorphic species, A.
It has been shown that the secondary forms of seasonallydimorphic butterflies do not all possess the tendency to revert in the same degree, but that this tendency rather varies with each individual.
Whether the colour and marking is adapted to the vine, as is the case with the two varieties of the dimorphic Chærocampa Capensis (q.
Machaon and Podalirius, seasonally dimorphicin Spain and Italy, 74; P.
Caterpillars, pupæ and eggs of summer and winter generations of seasonally dimorphic butterflies alike, 64.
Of the truth of this proposition there can be no doubt, after what has been above stated concerning the difference between the two forms of any seasonally dimorphic species.
Here again the case is quite similar to that of seasonally dimorphic butterflies.
A case of this kind, in which the winter form of a seasonally dimorphic butterfly occurs in other habitats as the only form, i.
Nevertheless, it cannot be denied that seasonal dimorphism occurs also in some species which do not hibernate as pupæ but as caterpillars; as, for instance, in the strongly dimorphic Plebeius Amyntas.
If it be asked what significance attaches to the duplication of the winter form, it may be answered that the species was already dimorphic at the time when it appeared in only one annual generation.
With respect to dimorphic plants: it is a great puzzle, but I fancy I partially see my way--too long for a letter and too speculative for publication.
Such direct action has of course been proved to occur in the case of several dimorphiclarvae (e.
Dimorphic branches in tropical crop plants: cotton, coffee, cacao, the Central American rubber tree, and the banana.
It is possible to raise from dimorphic species, both long-styled and short-styled illegitimate plants, and from trimorphic plants all three illegitimate forms.
After arriving at these conclusions, I was led to investigate a subject which throws considerable light on hybridism, namely, the fertility of heterostyled or dimorphic and trimorphic plants, when illegitimately united.
Dimorphic and trimorphic plants, though they are hermaphrodites, must be reciprocally crossed, one set of forms by the other, in order to be fully fertile, and in some cases to be fertile in any degree.
My observations 'On the Character and hybrid-like nature of the offspring from the illegitimate union of Dimorphic and Trimorphic Plants' were published in the 'Journal of the Linnean Soc.
So that with dimorphic species two unions, which may be called legitimate, are fully fertile, and two, which may be called illegitimate, are more or less infertile.
This appears all the more probable, if we admit that the structural differences between the forms of dimorphic and trimorphic plants, as the length and curvature of the pistil, etc.
We shall clearly understand why monoecious and dioecious,--why dichogamous, dimorphic and trimorphic plants exist, and many other such cases.
I hope also to republish a revised edition of my book on Orchids, and hereafter my papers on dimorphic and trimorphic plants, together with some additional observations on allied points which I never have had time to arrange.
On the Two Forms, or Dimorphic Condition, in the species of Primula, and, on their remarkable Sexual Relations.
On the character and hybrid-like nature of the offspring from the illegitimate unions of dimorphic and trimorphic plants.
In the second place, the older phyletic form may not be abandoned while a newer form is being developed therefrom, but the former may alternate with the latter, as we see in the case of seasonally dimorphic butterflies.
Thus, in all seasonally dimorphic species we find that the caterpillars of butterflies which are often widely different in the colour and marking of their successive generations are absolutely identical.
On the other hand, many species can be adduced of which the larvæ are dimorphic whilst the imagines occur only in one form (compare the first and second essays in this volume).
During the same year I published in the Journal of the Linnean Society, a paper On the Two Forms, or Dimorphic Condition of Primula, and during the next five years, five other papers on dimorphic and trimorphic plants.
The last six cases of mimicry are especially instructive, because they seem to indicate one of the processes by which dimorphic forms have been produced.
Romulus is probably a dimorphic form of the female P.
In this case, as in the last, distinct species, local forms, and dimorphic specimens, have been confounded under the common appellation of varieties.
The explanation seems to be that (like the two southern wheatears) these two wagtails are not specifically distinct, but merely a dimorphic form.
This would take you only a few minutes, and is the only way I see that I can find out whether these plants are dimorphicin this peculiar way--i.
The occurrence of dimorphic and non-dimorphic species in the same genus is quite the same as I find in Linum.
Pages 91-2, similar case with Auricula; on the other hand a non-dimorphic variety of P.
Now when you have completed your work you should draw up a paper, well worth publishing, and give a list of all the dimorphic and non-dimorphic forms.
Some dimorphic plant will probably prove too sterile for you to raise offspring; and others too fertile for much sterility to be expected in their offspring.
What I meant in my paper on Linum about plants being dimorphic in function alone, was that they should be divided into two equal bodies functionally but not structurally different.
On the two Forms, or Dimorphic Condition, in the Species of the Genus Primula," "Linn.
What a number of dimorphic plants South Brazil produces: you observed in one day as many or more dimorphic genera than all the botanists in Europe have ever observed.
All dimorphic and trimorphic plants present such difference in function and in size.
If you can find a dimorphic Oxalis it will be a new point, for all known species are trimorphic or monomorphic.
I have not heard of any dimorphic species in this family.
Villarsia are dimorphic in Europe and Ceylon; a sub-genus of Erythroxylon (675/3.
I have described in my paper 'On the Illegitimate Unions of Dimorphic and Trimorphic Plants' this remarkable variety, which was sent to me from Edinburgh by Mr. J.
I have shown in my paper on dimorphic plants that this species is commonly raised in England from self-fertilised seed, and the plants from having been cultivated in pots have been subjected to nearly uniform conditions.
A non-dimorphic species, which is fertile with its own pollen, but is extremely sterile if insects are excluded.
These latter plants cannot fail to act on each other likedimorphic or trimorphic species, in which the union of two individuals is necessary for full and normal fertility.
No one until lately would have imagined that in dimorphic and trimorphic plants the different lengths of the stamens and pistils, and their arrangement, could have been of any service, but now we know this to be the case.
So that with dimorphic species two unions, which may be called legitimate, are fully fertile; and two, which may be called illegitimate, are more or less infertile.
So it is with the reciprocally dimorphic and trimorphic plants previously alluded to.
So it is, as I have myself observed, with some dimorphic plants.
The umbilical scar, a sexually dimorphic character in Heterodon platyrhinos.
In the previous chapters various heterostyled dimorphic plants have been described, and now we come to heterostyled trimorphic plants, or those which present three forms.
Nature of the offspring from illegitimately fertiliseddimorphic plants.
But the results are much more complicated than with ordinary plants, as two heterostyled dimorphic species can be intercrossed in eight different ways.
With dimorphic species two illegitimate unions, and with trimorphic species twelve are possible.
Mr. Leggett suspects that it is either dimorphic or trimorphic, for the pollen-grains of the longer stamens are "more than twice the diameter or than eight times the mass of the grains of the shorter stamens.
They were called by me dimorphic and trimorphic, but have since been better named by Hildebrand, heterostyled.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "dimorphic" in a variety of sentences. We hope that you will now be able to make sentences using this word.
