Botany and horticulture.
Darwin's New Book.*
BY PROF. W. J. BEAL.
It seems to be the general opinion of all who are prepared and competent to judge, that Mr. Darwin has produced a most wonderful book,— as I believe, one which has not been excelled in importance to the farmer by any work in this or in any age. 

It is not easy reading, even to the botanist who is most familiar with the subjects treated. The author has recorded in a book of about 500 pages, a vast number of experiments and observations made, and in many cases often repeated, during a period of ten or twelve years. He has crossed the flowers, sowed the seeds and measured the heights of the plants, weighed or counted the seeds and capsules, often two or three times for many years, of several specimens of plants belonging to 57 species, of 52 different genera of 30 families. These are natives of very different parts of the world. He has made a book choke-full of information, valuable to the gardener and farmer, yet, in the words of the Gardener's Chronicle, "It is certain that these practical results will be a long time filtering into the minds of those who will eventually profit most by them." If the results are so valuable, and if much time must be occupied in reaching the understanding of farmers, this slow process cannot begin too soon, nor can its advantages be kept too persistently before their minds. 

"There is weighty and abundant evidence that the flowers of most kinds of plants are constructed so as to be occasionally or habitually cross-fertilized by pollen from another flower, produced either by the same plant, or generally, as we shall hereafter see reason to believe, by a distinct plant. Cross-fertilization is sometimes ensured by the sexes being separated, and in a large number of cases by the pollen and stigma of the same flower being matured at different times. It is also ensured, in many cases, by mechanical contrivances of wonderful beauty, preventing the impregnation of the flowers by their own pollen. Again, there is a class, in which the ovules absolutely refuse to be fertilized by pollen from the same plant, but can be fertilized by pollen from any other individual of the same species. There are also very many species which are partially sterile with their own pollen. Lastly, there is a large class in which the flowers present no apparent obstacle of any kind to self-fertilization; nevertheless these plants are frequently intercrossed, owing to the prepotency of pollen from another individual or variety over the plant's own pollen." 

There are, however, some cases which seem especially contrived for self-fertilization. The number is much smaller than would be supposed by a hasty observation. 
Andrew Knight, more than seventy-five years ago, said that  Nature intended that a sexual intercourse should take place between neighboring plants of the same species." Mr. Knight, and many since his time, practiced cross-breeding plants quite extensively, for the purpose of obtaining new and improved varieties. At present, there are many experts in this art in Europe and in this country. 

By cross-fertilization is meant "a cross between distinct plants which were raised from seeds and not from cuttings or buds." In the proper sense, then, we could not cross a flower of one Northern Spy apple-tree with the flower of another tree of the same variety, as they have all come from the grafts or buds of one seed. In like manner, it would not be a cross to fertilize a flower of the General Grant geranium with others of the same variety, because all our plants have come from cuttings of one parent plant, or sonic of its descendants. 

Many of Mr. Darwin's plants were raised from seeds which were sown at the same time, near each other. The best young plants from the seeds of crossed flowers, and the best which came from self-fertilized flowers were planted on opposite sides of the same pot, where the soil was well mixed. " In comparing the two sets, the eye alone was never trusted." 

Fifteen plants of Indian corn from crossed seed exceeded in height fifteen others from self-fertilized seed, as 100 exceeds 84. He experimented with plants of the common Morning Glory for ten generations, using the same number of plants from crossed plants as from those self-fertilized. The average in height for the ten years is as 100 to 77 in favor of the crossing. 

The flowers of this plant are freely crossed if left to themselves, exposed to insects. It is, then, altogether likely that the seeds with which Mr. Darwin began were from crossed flowers, yet, in the first generation, the seeds of crossed plants exceeded those self-fertilized as 100 exceeds 76. If we compare the number of seeds and capsules produced in the first generation, the crossed plants exceeded the others as 100 exceeds 64. The relative superiority of the crossed plants is chiefly due to their producing a much greater number of capsules, and not to each capsule containing a larger average number of seeds. When self-fertilized for nine generations, the flowers were of a uniform tint, as those of a wild species, while those in the beginning were of various colors. The crosses, so far mentioned of the flowers of Morning Glory, refer to crosses of different plants raised in the same garden, year after year. After nine generations, he introduced seeds raised at a distance, under different circumstances. Plants from these were crossed with plants which had been intercrossed in his garden. This cross (called the Cochester-crossed) exceeded in height the other intercrossed plants of the tenth generation, as 100 exceeds 78. In number of capsules, they were to each other as 100 to 57, and the capsules, in weight, as 100 to 51, in favor of those crossed with foreign stock. 

Here we get a most important fact, not learned by Mr. Knight, or any one else, that a cross from a fresh stock increases the size of plant and its fruitfulness, probably owing to their differing somewhat in constitution or character. The 
*The effects of cross and self-fertilization of plants, by Charles Darwin

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crossing of closely related plants is generally an improvement over self-fertilization; but, crossing with foreign stock of the same variety, is a far greater improvement. 

The proof of the truth of the above sentence in italics is worth untold sums to the raiser of vegetables, the florist, the pomologist, to the general farmer. 

In the sixth generation of the self-fertilized Morning Glory, appeared a single plant which conquered its crossed opponent by half an inch in height. Its descendants continued vigorous and fertile, even when self-fertilized. They were not profited by a cross with a distinct stock. Mr. Darwin adds that if this latter part is trustworthy, it is a unique case, as far as he has observed in all his experiments. 

Agricultural College, Lansing, Mich., April 28, 1877.