(387/1. The following refers to Blytt's "Essay on the Immigration of the Norwegian Flora during Alternating Rainy and Dry Periods," Christiania, 1876.)
I thank you sincerely for your kindness in having sent me your work on the "Immigration of the Norwegian Flora," which has interested me in the highest degree. Your view, supported as it is by various facts, appears to me the most important contribution towards understanding the present distribution of plants, which has appeared since Forbes' essay on the effects of the Glacial Period.
LETTER 388. TO AUG. FOREL. Down, June 19th, 1876.
I hope you will allow me to suggest an observation, should any opportunity occur, on a point which has interested me for many years—viz., how do the coleoptera which inhabit the nests of ants colonise a new nest? Mr. Wallace, in reference to the presence of such coleoptera in Madeira, suggests that their ova may be attached to the winged female ants, and that these are occasionally blown across the ocean to the island. It would be very interesting to discover whether the ova are adhesive, and whether the female coleoptera are guided by instinct to attach them to the female ants (388/1. Dr. Sharp is good enough to tell us that he is not aware of any such adaptation. Broadly speaking, the distribution of the nest-inhabiting beetles is due to co-migration with the ants, though in some cases the ants transport the beetles. Sitaris and Meloe are beetles which live "at the expense of bees of the genus Anthophora." The eggs are laid not in but near the bees' nest; in the early stage the larva is active and has the instinct to seize any hairy object near it, and in this way they are carried by the Anthophora to the nest. Dr. Sharp states that no such preliminary stage is known in the ant's-nest beetles. For an account of Sitaris and Meloe, see Sharp's "Insects," II., page 272.); or whether the larvae pass through an early stage, as with Sitaris or Meloe, or cling to the bodies of the females. This note obviously requires no answer. I trust that you continue your most interesting investigations on ants.
(PLATE: MR. A.R. WALLACE, 1878. From a photograph by Maull & Fox.)
LETTER 389. TO A.R. WALLACE.
(389/1. Published in "Life and Letters," III., page 230.)
(389/2. The following five letters refer to Mr. Wallace's "Geographical Distribution of Animals," 1876.)
{Hopedene} (389/3. Mr. Hensleigh Wedgwood's house in Surrey.), June 5th, 1876.
I must have the pleasure of expressing to you my unbounded admiration of your book (389/4. "Geographical Distribution," 1876.), though I have read only to page 184—my object having been to do as little as possible while resting. I feel sure that you have laid a broad and safe foundation for all future work on Distribution. How interesting it will be to see hereafter plants treated in strict relation to your views; and then all insects, pulmonate molluscs and fresh-water fishes, in greater detail than I suppose you have given to these lower animals. The point which has interested me most, but I do not say the most valuable point, is your protest against sinking imaginary continents in a quite reckless manner, as was stated by Forbes, followed, alas, by Hooker, and caricatured by Wollaston and {Andrew} Murray! By the way, the main impression that the latter author has left on my mind is his utter want of all scientific judgment. I have lifted up my voice against the above view with no avail, but I have no doubt that you will succeed, owing to your new arguments and the coloured chart. Of a special value, as it seems to me, is the conclusion that we must determine the areas, chiefly by the nature of the mammals. When I worked many years ago on this subject, I doubted much whether the now-called Palaearctic and Nearctic regions ought to be separated; and I determined if I made another region that it should be Madagascar. I have, therefore, been able to appreciate your evidence on these points. What progress Palaeontology has made during the last twenty years! but if it advances at the same rate in the future, our views on the migration and birthplace of the various groups will, I fear, be greatly altered. I cannot feel quite easy about the Glacial period, and the extinction of large mammals, but I must hope that you are right. I think you will have to modify your belief about the difficulty of dispersal of land molluscs; I was interrupted when beginning to experimentise on the just hatched young adhering to the feet of ground-roosting birds. I differ on one other point—viz. in the belief that there must have existed a Tertiary Antarctic continent, from which various forms radiated to the southern extremities of our present continents. But I could go on scribbling forever. You have written, as I believe, a grand and memorable work, which will last for years as the foundation for all future treatises on Geographical Distribution.