Isomorphism may be defined as the existence of two or more different substances in the same crystal form and structure, polymorphism as the existence of the same substance in two or more crystal modifications, and morphotropy (after P.
Since in Drosophila the results are explicable on a sex-linked basis, a similar explanation may apply to polymorphism in butterflies.
By suitable combinations of eosin and cherry most of the cases of polymorphism in butterflies may be simulated.
That caterpillars can also vary locally without thereby affecting the imagines is shown by the frequently mentioned and closely investigated cases of di- and polymorphism in the larvæ of a number of Sphingidæ (M.
There is much that is interesting to be said in regard to these species, but it would be out of keeping with the general tenor of this paper to give details of this very complicated case of polymorphism in P.
The tendency of the female to dimorphism and polymorphism has been of great importance in determining this predominance.
Moreover, such an extreme multiplicity of forms is interesting, since, so far as I know, polymorphism to this extent has not been observed in any insect.
Polymorphism does not here depend upon contemporaneous but upon successive double adaptation; displacement of the old by a new adaptation; proof in the cases of D.
For the reasons just given, I maintain that it is neither justifiable nor useful to designate the di- and polymorphism of butterflies as di- and polychroism, and thereby to attribute but little importance to these phenomena.
The theoretical bearing of thispolymorphism will be treated of subsequently.
I have long held the opinion that the di- and trimorphism displayed by certain butterflies has originated through polymorphism from ordinary variability.
The idea that alternation of generation is derived from polymorphism (not the reverse, as usually happens; i.
The third example of polymorphism I have to bring forward is Papilio Ormenus, which is closely allied to the well-known P.
The only other case of polymorphism in the genus Papilio, at all equal in interest to those I have now brought forward, occurs in America; and we have, fortunately, accurate information about it.
While, therefore, there is much evidence of a negative character against the existence of an extensive polymorphism among algae, some amount of metamorphosis is known to occur.
Intermediates, combining these qualities in various degrees, were abundant, and the condition of the species, which was the only representative of the genus in the locality, recalls the extreme polymorphism of many of the Noctuid Moths.
The polymorphism seems to be now at least a general property of the variable species, as the fixity is a property of the fixed species.
Such conditions should give good opportunity for polymorphism to be produced.
This particular example of polymorphism is but little limited by locality.
Just as in ages of domestication no rose has ever given off a blue variety so has the pheasant never broken out into the polymorphism of the Ruff.
All were beaten out of the same hedge, and their polymorphism is such that no one unaccustomed to such examples could suppose that they belonged to a single species.
A polymorphism offering a parallel to that of the variable moths is afforded by the breeding plumage of the Ruff, the male of Machetes pugnax.
These laws have the advantage of being applicable to the mutual transformations of isomers, whatever be the nature of the deeper origin, and so bring polymerism, metamerism and polymorphism together.
Similarly, the differences that exist among termites and ants, as Emery shows, may be described as polymorphism due to food.
As much as sexual dimorphism, the phenomena of polymorphism show the enormous influence exerted by external forces upon correlated variation of the parts during development, and in this way upon the final structure.
Emery explains this polymorphism by attributing it to the general laws of growth in the insect organism under the influence of different external stimuli.
To these two cases others were soon added, at first of inorganic, and later of organic substances, so that polymorphism is now recognized as of very frequent occurrence indeed.
Polymorphism was first observed by Mitscherlich[47] in the case of sodium phosphate, and later in the case of sulphur.
In this polymorphism of psychical defect is justification for the numbering of the tic patient with the vast crowd of degenerates, and indeed Magnan[20] is content to consider tic one of the multitudinous signs of mental degeneration.
As has been already remarked, the polymorphism of tics is such that the plan of treatment selected must be necessarily elastic if it is to be altered to suit individual cases.
Polymorphism is one of the tic's distinguishing features.
It illustrates the phenomena of polymorphism most beautifully.
The matter is further complicated by the fact that polymorphism is not uncommon, especially among the females of the mimetic forms.
But although the polymorphism exhibited by the females of a given species may be very marked, we do not find one of them resembling a Danaine and another a Pharmacophagus Swallow-tail.
Papilio polytes is one of the few mimetic species that has been bred, and in no other case of polymorphism is the relation between the different forms so clearly understood.
Another instance of experimental breeding involving polymorphism and mimicry in the female sex is that of the African Papilio dardanus, but the case is here complicated by the greater number of female forms (cf.
In consonance with this view is the fact that where polymorphism occurs among the females of a mimicking species the models, though often widely different in appearance, are, as a rule, closely related.
Others such as {142} the relative scarcity of mimicry in the male sex and the existence of cases of polymorphism among females of a species which cannot possibly be explained on mimetic lines have already been mentioned.
It is chiefly amongst the microscopic species that polymorphismhas been determined.
Cooke, "On Polymorphismin Fungi," in "Popular Science Review.
We have adduced in the foregoing pages a few instances which will serve to illustrate the polymorphism of fungi.
The other series of phenomena grouped together under the name of polymorphism relate to forms which are removed from each other, so that the mycelium is not identical, or, more usually, produced on different plants.
So much has been discovered during recent years of the polymorphismwhich subsists amongst the species in this section, that any detailed classification can only be regarded as provisional.
Some instances might be noted, not without interest, in which the facts of dimorphism or polymorphism have not been satisfactorily proved, but final judgment is held in suspense until suspicion is replaced by conviction.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "polymorphism" in a variety of sentences. We hope that you will now be able to make sentences using this word. Other words: diversification; diversity; multiplicity; variation; variegation; variety
