LETTER 207. TO J.D. HOOKER. Down, January 6th [1868]. Many thanks about names of plants, synonyms, and male flowers--all that I wanted. I have been glad to see Watson's letter, and am sorry he is a renegade about Natural Selection. It is, as you say, characteristic, with the final fling at you. His difficulty about the difference between the two genera of St. Helena Umbellifers is exactly the same as what Nageli has urged in an able pamphlet (207/1. "Ueber Entstehung und Begriff der naturhist. Art." "Sitz. der K. Bayer. Akad. Der Wiss. zu Munchen," 1865. Some of Nageli's points are discussed in the "Origin," Edition V., page 151.), and who in consequence maintains that there is some unknown innate tendency to progression in all organisms. I said in a letter to him that of course I could not in the least explain such cases; but that they did not seem to me of overwhelming force, as long as we are quite ignorant of the meaning of such structures, whether they are of any service to the plants, or inevitable consequences of modifications in other parts. I cannot understand what Watson means by the "counter-balance in nature" to divergent variation. There is the counterbalance of crossing, of which my present work daily leads me to see more and more the efficiency; but I suppose he means something very different. Further, I believe variation to be divergent solely because diversified forms can best subsist. But you will think me a bore. I enclose half a letter from F. Muller (which please return) for the chance of your liking to see it; though I have doubted much about sending it, as you are so overworked. I imagine the Solanum-like flower is curious. I heard yesterday to my joy that Dr. Hildebrand has been experimenting on the direct action of pollen on the mother-plant with success. He has also succeeded in making a true graft-hybrid between two varieties of potatoes, in which I failed. I look at this as splendid for pangenesis, as being strong evidence that bud-reproduction and seminal reproduction do not essentially differ. My book is horribly delayed, owing to the accursed index-maker. (207/2. Darwin thoroughly appreciated the good work put into the index of "The Variation of Animals and Plants.") I have almost forgotten it! LETTER 208. TO T.H. HUXLEY. Down, January 30th [1868].