59

(53

Hybridism

(On the characters & differences of hybrid mongrels, independently of their fertility)

Long as this chapter has been it has as yet been devoted solely to the important subject of the fertility sterility of hybrids & fertility of mongrels;  We must now compare at much less length the hybrid offspring of two distinct species & & the mongrel offspring of two varieties of the same species (as variously considered) & see how far they resemble or differ in other respects from each other quite independently of in each their fertility. This important subject for us, for it wd be strange if for [illeg], like from produced by interm causes. — many have tend yet slowly to return / if it shd be shown alike, only case, agent [illeg] organ.— /Plants/ For animals side I will put law of [illeg] Plant & that of animals.— (As some authors have considered (Jour Transact Lyon Acad.) hybrids as monsters & therefore apparently, but falsely, as beyond the pale of the law, it will be well to premise that Gaertner & Kolreuter have very clearly shown that this is not far from the case; undoubtedly hybrids of each species follows distinct laws in their resemblance to their parent species like individuals to the species, for when the same two species are repeatedly crossed the hybrids of the (at least of the first generation) are alike, (Bastarderzeugung p. 234) & where rarely an "exceptional types", resembling clearly to their parents are produced, these are reproduced at long intervals similar (p 238) (& when they yield can propagate, they generally return p 424 to the normal types hybrid type, nor do malconformations (G. p. 518, 557) occur oftener in hybrids than in pure species; in fact not even in their reproductive organs, which, as we have before remarked, are only (in most cases) functionally imperfect.

Gaertner has compared in detail hybrids & mongrels, beisdes fertility, he reduces, the two differences to two (& it is evident that he wd gladly have found others) (Bastard p. 582) owing to a greater tendency in mongrels to go return to the parent-forms, & secondly to mongrels especially in the first generation, but likewise in the succeeding generations being. more variable than even than with respect to the successive generations of true hybrids. True, with respect to this latter point difference of great variability in the first generation (Gaertner, however, repeatedly admits p 445) that true hybrids in the successive generations whether fertilised, inter se by their own pollen, or whether being reduced to or by that of either parent are

60

(54

Hybridism

518, extremely variable & indeed that it is the chief characteristic of Hybrids, & Kölreuter— (Nova Acta 1794. p. 391) uses the strongest expressions on this head , as does Herbert, Amaryllid p.348. But there can, I apprehend, be no doubt But it is rule not universal that in the first generation hybrids have much more fixed character than mongrels; but this, I think, might almost have been expected, for as variability itself is known to be tendency, & as varieties are either supposed or when positively known to be such, generally must have varied within recent times it is not strange that their offspring shd. be more variable . Again far the majority of—varieties occur in cultivated plants, & Gaertner admits that the hybrids from these than the offspring of pure & unvarying species. But "exceptional types", which are nothing else but strongly marked varieties, (p. 238) do occur occasionally amongst true in the first generation of undoubted hybrids; will [illeg] as do lesser variations (p 249) 249 but he remarks, that he has not observed them in the endemic plants them only in long cultivated plants, which by this very process must very probably have been brought almost into the condition of varieties. //in fold on subject of Variation, laws of s. 249. & Kolreuter.

It is important also to observe that these slight lesser? variations in the character of hybrids in their first generation, & therefore strictly analogous with the variability of mongrels, occur principally in species species such so close species (p 247 p. 577) that they have been thought by many authors to be mere varieties; so that as far as this goes the

61

(55

Hybridism  

difference between hybrids & mongrels graduate away just in the same way as fertility does.*

(*The above statement by Gaertner seems in some degree contradicted by another statement that  move on to variety of hybrid in this 1st gen. is somehow governed by laws utterly inexplicable by laws: then,. With respect (however) with respect (however) to all such comparisons as the last, it shd. be borne in mind that varieties have been but little crossed systematically; & Gaertner does not give his facts in detail; & I must doubt whether all mongrels are sp more variable in their first generation than are hybrids in their first: Kölreuter gives details an account of some crosses & reciprocal crosses between several vars of Mirabilis, (Salvia Papaver Flowers), stocks of two colours, of Tobacco two varieties and of Digitalis (Dritte Zweite Fortsetz p 56, p. 126, 128: Journal de Physique 1782. p. 285 ): Nova Acta Petrop. 1795 p. 333. et 1797 p. 393) & no mention is made of extreme variability, which the general nature tenor of Kölreuter's works makes it almost certain that he would. have done. Even if it could be shown that mongrels in their first generation did vary far more than hybrids, & that their differences did not graduate away, & could not be accounted for by the long cultivation of those plants which have commonly produced exist varieties, even then I doubt whether the differences would be considered very essential, because we find stated by Gaertner that between different kinds of undoubted hybrids there is an difference, utterly inexplicable, in the tendency to vary: thus (p 445) such a hybrid as Dianthus barbato-barbatuscarthusianorum gives more varieties then

62

(56

Hybridism  

D. barbatocarthusianorum — barbato carthusianorum: again offspring from Lobelia fulgens ♀ — Cardanalis-syphitica (m)  are more variable (p 507, 513) are more variable than when the mother is the hybrid & the third species is the father, as Lobelia cardanilis-fulgens (f). — syphitica(m) —

With respect to the second & last other main difference  between mongrels & hybrids as specified by Gaertner (p 582), viz that they mongrels have a stronger tendency to go back to the pure parent forms than have hybrids, & this indeed is only one variety I must repeat my remark, that there really is not sufficient evidence in regard to mongrel to form any definite conclusion. In crossed cabbages, seems in the first generation, there certainly seems, according to Wiegmann— (a)

Undoubtedly it can only be a difference in degree, for Gaertner gives many facts (p 420 - 446) showing that simple hybrids & hybrids fertilised by their pollen of their mother-species in their successive generations occasionally sport back towards the pure ancestral forms: Kölreuter gives other cases (Dritte Fortsetz. p. 53, 59.) & details one remarkable case, (though this might equally be advanced on either side of the argument), that the of the hybrid offspring from the hybrid Mirabilis Jalapa longiflora fertilised by vars. of M. jalapppa, which took after J M. jalapa if child there is 3/4 blood or even after M. longiflora, of which there is only quarter blood, rather than after the hybrid mother, One statement (however) by Gaertner would lead to the inference there was some var essential difference in the going back the tendency to reversion of in the successive

62v

(a) (Ueber den Bastarderzeugung 1828 p. 8, 32) in most of the experiments a strong tendency to go back; but he adds (p. 33) as a general rule the mongrels in the third generation kept their blended character.—  Hybrid Turnips— Hybrid Scotch kale

63

(57

Hybridism

generations of hybrids & mongrels namely that (p. 444 p. 421 p. 236) these reversions have not been observed in the most fertile hybrids, in which  only coming nearest on the view of species graduating into varieties to mongrels they might have been expected: the number of these very fertile hybrids which preserve their hybrid type is few, p. 553) & it is quite possible if mongrels were equally well known such would be found amongst plants: some do appear to occur in the animal kingdom.—

With the exception of their few external differences putting on one side  the question of fertility if they really are essential differences, just posited, only namely the greater variability of mongrels in the first generation, & their greater tendency to revert to the parent forms in successive generations, in all other respects (we are have been already (discussing there seems to be in after all all other, respects a very close resemblance as far as fact alone is the judge or rather identity in hybrids & mongrels. Both are remarkably luxuriant, hardy. & precocious. Both are generally come alike from reciprocal crosses.* In regard to of the degree of laws of resemblance likeness of mongrels & hybrids respectively to their two species hybrids Gaertner considers cl. as  —  parents; in the first place if hybrids first resembled in regard to hybrids Gaertner p. 277-294 has well classified them in accordance with their into resemblances to their parents into three classes, namely (1st strictly hybrids very many intermediate hybrids in their whole structure: secondly their & M very commonly those with one parent more like the father-species & another part more more like the mother-species, but:— no case with those of their structure identically the same with either parent, & thirdly with hybrids (decidente typus) very decidedly

64

(58

Hybridism

to be resembling in the parent: but Gaertner most fully admits that these divisions certainly blend together, but & that it is often very extremely difficult to say or whether a part of a hybrid wd most like in which class a hybrid should be placed. It is  it is important to observe that, according to Gaertner (p 282) the intermediate types are most commonly observed in the hybrid offspring of closely allied species, p. 59 for successive generations & likewise commonly (p 578) of mongrels commonly in the mongrel offspring of varieties. variable & self; from what everyone sees in the offspring of man & of our domestic animals, it seems to me that their  blending resemblances to their parent are exactly the same as those classed by Gaertner; how often one sees a child in pretty nearly intermediate, still more often with one feature or part of the body like one parent, & another part the other parent; & occasionally a child taking almost entirely after the either one of its two parent.

It is by this latter class of resemblance facts alone, might appear to one, that it can be explained, namely certain families, having a prepotent power of impressing within point of stamen. (Gaertner has shown that certain species (p 290 Gattungsystem) have a prepotent power (quite distinct from their fertilising power) of analogous affecting, or impressing their likeness on, their hybrid offspring: I cannot doubt that this is the case with varieties of plants, for we see it, as it appears to me, even in certain families of mankind; for in no other way, can it be those

65

(59

Hybridism

often quoted instance of a certain characteristics, as the nose of the Austrian Emperors, long continuing in a family after repeated marriages into other families.— (*give cases in note)  

(In the successive generations after the first of Hybrids & of mongrels, the offspring of both are extremely variable, though I know of only one case in which mongrels have been observed during several generations, namely two varieties of Mirabilis described experimented on by Kölreuter (Nova Acta Petrop. 1797 p. 393) for during four generations. And Gaertner says (p 580 581) that besides in the differences already specified, the successive generations of both that they produced mongrels can be classified in the same way, & have similar qualities.)

66

61

(Gaertner has discussed at great length (p. 455) what may be called the reduction of one species into another;— that in the crossing of a hybrid with one of the parent forms over & over again till the best offspring is undistinguishable from the pure form. To effect this more than 6 or 7 generations are never required; but even when the same species are employed the number of generations varies apparently depending on the varieties & even on the individuals (p. 458 461, 465) employed: taken, & whether they have been subjected to cultivation: those species which have an prepotent especial power of impressing their likeness on their offspring (p. 470) Naturally can re convert the final hybrid form into the pure form in the fewest number of generations: generally species (p. 468) which are very remotely allied have less sexual affinity require a greater number of generations to reduce each other than species more nearly allied easily crossed or united.— I am not aware that any systematic attempt has been made in the vegetable kingdom to reduce a mongrel by repeated crossing with either pure parent form; to their but there can be no doubt from this process having been often done carried on in the animal kingdom, that it would be effected, & probably more easily than in true hybrids, owing to closer relationship

67

(62

Hybridism

of the parents. From facts, however, well known in the animal kingdom it is probable that in some cases many generations would ensue before every trace would be lost of the one original pure parent variety, especially if that variety had a strong power of impressing its likeness on its offspring. From some of the facts admitted by Gaertner, there can be hardly a doubt that in reducing the same mongrels to the pure forms at different the number of generations required to reduce even the same mongrel would often be variable. Gaertner considers (p 475) that the capacity of a hybrid being reduced absorbed into either pure parent form, (is not this self return ?) as an "unequivocal proof" that these species have fixed limits & must will always return to the original parent-form. This appears to me an extraordinary conclusion from the premises; as certainly Gaertner would not dispute that our a cultivated variety & therefore not a wild aboriginal form could absorb one side by crossing be made easily to reduce or absorb another variety; as indeed has been done with the animals; kingdom, for instance a cross has been made between a grey-hound & bull-dog, & by repeatedly crossing the mongrels with pure greyhound, every external trace of the bull-dog has been lost , excepting more courage & pertinacity. Indeed an exactly opposite view to had the facts been exactly the reverse to what they are, Gaertner's might have been argued with much more plausibility that species have "fixed & impassable limits"; for if in crossing

68

(63

Hybridism

two forms supposed to have been created distinct, it had been found impossible to eliminate all trace of one, this might have been triumphantly adduced to show the difference between species & many temporary variations. When poultry are have once been crossed with the Malay breed, it is very difficult for many generations to get away the stain; & I have heard this adduced, with It. as a proof that the Malay is an aboriginally distinct breed.—

It had always appeared to me ⸮ in some degree seems I had thought it probable that if a variety, of the same species producing var were crossed with one another an unaltered wild species were crossed with a variety produced by long cultivation, the wild varying father would not impress its likeness on the hybrid offspring with so much force as the wild unaltered species: but from some few experiments made by Kölreuter in which (1st Fortsetzung p.29) he crossed varieties of tobacco with an unaltered wild species; & likewise (3rd Fort. p. 72, 79, 83, 87, 103 but in the 2nd Fort. p. 116, there is case somewhat opposed) several long-cultivated forms of Dianthus with wild species, this does not seem to hold good be the case; & a variety hybrid from between a variety of one species & a second unaltered species seems as often to come intermediate in structure, as between from from between two unaltered species.

Gaertner, guided perhaps by some such idea as that given given in the last paragraph, (p. 273, 581) lays great stress on the supposed fact that if two distinct, but very closely alike allied species are crossed with a third

69

(64

Hybridism

species, the hybrids are very distinct from each other, even more distinct than the pure species; whereas if two varieties of one species are compared with another a distinct specimen, the hybrids differ very little. In regard to the latter statement But in regards to varieties no other facts whatever are given but some two sets of crosses of several varieties of two species of tobacco with two other distinct species. And Now it so happens that this   Kölreuter (1st Fortset p. 31: to 2d Fort. p. 56), also crossed several varieties of tobacco with a distinct species & he expressly states that the hybrids differed only as much as might have been expected from as the difference between the varieties employed [illeg] & as quite both cd be expected. Again Kolreuter crossed (Journal de Physique 1782 p. 285) digitalis thapsi & D. purpurea, which (p 291) he had found to be varieties of the same species, with D. lutea, & the hybrids seem to differ about as much as the might have been expected from the differences of D. thapsi & purpurea.— As far as mere colour is concerned it is very clear that the yellow & white  varieties of one species of Verbascum after the hybrids (3d Fortset p. 6, 34): Acta acad. Petrog: 1781 p. 249 p. 257) are when crossed with a distinct species, yield the hybrids having differently colored flowers. In as much as two varieties generally differ from each less than two species, of naturally hybrid from two varieties with another this species would more closely resemble each other, than two hybrids from two distinct species with a than another species. Even Gaertner, I apprehend, would not doubt that a red common or wild cabbage