I end my discussion by doubting, because all cases of monstrosities which resemble normal structures which I could find were not in allied groups. Trees like Aspicarpa (95/5. Aspicarpa, an American genus of Malpighiaceae, is quoted in the "Origin" (Edition VI., page 367) as an illustration of Linnaeus' aphorism that the characters do not give the genus, but the genus gives the characters. During several years' cultivation in France Aspicarpa produced only degraded flowers, which differed in many of the most important points of structure from the proper type of the order; but it was recognised by M. Richard that the genus should be retained among the Malpighiaceae. "This case," adds Darwin, "well illustrates the spirit of our classification."), with flowers of two kinds (in the "Origin"), led me also to speculate on the same subject; but I could find only one doubtfully analogous case of species having flowers like the degraded or monstrous flowers. Harvey does not see that if only a few (as he supposes) of the seedlings inherited being monstrosities, Natural Selection would be necessary to select and preserve them. You had better return the "Gardeners' Chronicle," etc., to my brother's. The case of Begonia (95/6. Harvey's criticism was answered by Sir J.D. Hooker in the following number of the "Gardeners' Chronicle" (February 25th, 1860, page 170).) in itself is very curious; I am tempted to answer the notice, but I will refrain, for there would be no end to answers. With respect to your objection of a multitude of still living simple forms, I have not discussed it anywhere in the "Origin," though I have often thought it over. What you say about progress being only occasional and retrogression not uncommon, I agree to; only that in the animal kingdom I greatly doubt about retrogression being common. I have always put it to myself--What advantage can we see in an infusory animal, or an intestinal worm, or coral polypus, or earthworm being highly developed? If no advantage, they would not become highly developed: not but what all these animals have very complex structures (except infusoria), and they may well be higher than the animals which occupied similar places in the economy of nature before the Silurian epoch. There is a blind snake with the appearances and, in some respects, habits of earthworms; but this blind snake does not tend, as far as we can see, to replace and drive out worms. I think I must in a future edition discuss a few more such points, and will introduce this and H.C. Watson's objection about the infinite number of species and the general rise in organisation. But there is a directly opposite objection to yours which is very difficult to answer--viz. how at the first start of life, when there were only the simplest organisms, how did any complication of organisation profit them? I can only answer that we have not facts enough to guide any speculation on the subject.