My dear Sir,

Many thanks for your letter of March 27.¹ I fear, in the present state of your health, I am troubling you too often with my scribblings; but the remedy is an easy one & in your own hands—throw them in the fire.

I was delighted with your Linum & Primula papers, & also with M^r. Scott’s paper on Primulaceæ.² What a remarkable fact that is which he brings out, that the red variety of the common Primrose absolutely refuses to intercross with the normal form.³ Such facts as these, it seems to me, knock the ground away completely from under the Creative Theory.

As to “Unity of Coloration” you have yourself given one very good example in the stripes which re-appear more or less in the several species of the genus Equus. ⁴ Another instance is found in the fawn of our common deer being spotted like many adult fallow deer, & Prof. Haldeman⁵ writes me word that he has remarked on the rump in cervus & antelope “being frequently of a lighter tint than the general color”. (Freshwater Univalve Mollusca N^o 7. Jan 1844 Planorbis p. 5)⁶   There is another most remarkable one in the Owlet-moths (Noctuadæ), in almost every genus of which the “orbicular” & “reniform” spots are found, besides five transverse lines of color which Guenée calls respectively the “basal”, the “transverse anterior”, the “transverse posterior”, the “subterminal” & the “terminal”.⁷ From the enormous number of species in Insects, an Entomologist is naturally led to notice such things more than other Naturalists. I am not sufficiently familiar with exotic species of Insects to say whether or not genera inhabiting two continents “sometimes display a somewhat different type of coloring”.⁸ But ever since I have been collecting in this country I have been struck almost every day by the same genera on both sides the Atlantic displaying the same coloration. For example, I have two N.A. species of Panagæus in my collection, (P. fasciatus Say, & cruciger Say) which imitate your P. crux-major both in design & color; yet with the exception of the Lebia & Bembidium groups, almost all other Carabidæ are of plain colors. If then there is no genetic connection between the N.A. & European species of Panagæus, & if (as I think we must concede) coloration is independent of structure, why should Panagæus, on both sides of the Atlantic, have four more or less confluent large red spots arranged in a quadrangle on its elytra?

My idea as to the mode in which Cecidomyia acquired its gall-producing poison,⁹ is that originally they were all without it, as are to this day the Hessian fly (C. destructor) & the Wheat-midge. (Cec. tritice). But that individuals by Variation acquired the power of secreting a minute portion of poison so as to irritate the plant slightly & cause a slight additional flow of sap, & a better nidus for the future larva,, whereby they gained an advantage over their fellows & so on according to your theory. Whether the Guest-flies are degraded Gall-flies, or in an incipient state of perfection, is perhaps a doubtful point, though I rather incline to the former hypothesis.¹⁰

As to Wagner’s theory of Viviparous larvæ,¹¹ allowing it as you say to be a form of gemmation, ought we to expect to find a mode of reproduction characteristic of the Vegetable Kingdom, & hitherto only met with in Animals of very low type, in such highly organized & intellectual beings as Insects? Taking everything into consideration, I think Insects are superior to Fish, & could you yourself swallow down gemmiparous Fish without very good Ichthyological authority? I couldn’t. Now if a Fish, which has no “penis intrans”,¹² which inhabits the water still & which still breathes through gills, is not found to be gemmiparous, I am loath to believe that an insect can be so. Still, facts are stubborn things, & it may turn out that Wagner & Co are right, though I still believe he was deceived by parasitic larvæ.¹³

In a brief review of Wagner’s book which I have lately seen reference is made to a genus Daphnia & Family Daphnidæ, in which both males & females are said to produce parthenogenic eggs in the summer, & another kind of eggs called “ephippia” in the winter.¹⁴ To what class do these extraordinary animals belong? Can it be possible that true males generate eggs?

I bought a few weeks ago Lyell’s Book on the Antiquity of Man,¹⁵ & was highly delighted with it. I had no idea that Prof. Owen was capable of making such an ass of himself as he has done¹⁶ ⁠⟨⁠section excised⁠⟩⁠

You have referred in the “Origin” to a (dipterous?) fly checking the propagation of cattle & horses in the southern parts of South America.¹⁷ I find that in Gen. Páez’s book on South America (p. 58) he says that in the Northern parts (Venezuela &c) a fly called ‘gutano’ oviposits in the umbilicus of newly born foals so constantly, that the herdsmen have to examine all the young foals & remove the larva, or otherwise the foal is sure to die.¹⁸ May we not account for the extinction of the Horse in America by some such means as this?

Ever yours very truly, | Benj. D. Walsh

⁠⟨⁠section excised⁠⟩⁠ the so-called ⁠⟨⁠remainder of line excised⁠⟩⁠ I am as unwilling to believe in gemmiparous insects as in hermaphrodite insects. Both seem to me low forms of reproduction derived originally from the Vegetable Kingdom & dropped in the march of development at an early period.