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LITERATURE.

The Variation of Animals and Plants under Domestication. By CHARLES DARWIN, M. A., F. R. S., &c. Authorized Edition, with a Preface by Professor ASA GRAY. In two volumes, with illustrations. (Orange Judd & Company, 245 Broadway.) Readers of Darwin's " Origin of Species" will remember that that work only professed to be a very general statement of a theory which needed a great deal of elaboration and illustration; so much indeed that the author was in doubt whether his life and health would serve him long enough to carry out his plan, and therefore gave us the outline of his theory, which, if circumstances favored, he promised in time to fill out. The present work is the first instalment of the complete work. Consisting of two volumes of more than one thousand pages in all, it only covers the first chapter of the original work, which treated of variation under Domestication. In a second work he now proposes to treat of the variation of Plants and Animals in a state of nature, i.e. of natural selection. In a third work he will apply the principles established in the second to several large and independent classes of facts, such as the geological succession of organic beings, their distribution in past and present time, and their mutual affinities and homologies. He has, indeed, set himself an almost endless task, and one that would certainly discourage a less earnest and calmly enthusiastic man. All lovers of the truth will pray that he may live to bring it to completion; for though the fairness of his dealings and the fascinations of his theory have drawn after him a host of followers, many of whom are doubtless capable of carrying on this work, even from this point, in a very creditable manner, yet it is hardly to be hoped that another could bring to it Darwin's own peculiar fitness for the task.

The scope of the present work is so much narrower than the last, that it will be found, and especially the first volume, much less interesting. But the wonder is, that without the least apparent effort to make it interesting, it is so to such an extent. The first volume, in particular, is mainly a collection of facts showing to what extent animals and plants vary under domestication. But let no one think that these facts are such as none but men of science can comprehend and enjoy, for it is not so. It must be a very dull understanding that does not care to note their orderly array. The wonder is that a book of this sort can so draw us to its author. In scientific works it is generally very little that we "read between the lines." But here it is quite different, and from the perusal of the book we have arisen with a sense that Darwin is one of those "persons one would wish to have seen," so deeply do his pages impress us with a sense of his perfect candor and sincerity. He is never a partisan, never a special pleader. He states the objections to his theory more strongly than they have ever been stated by any body else. His sole desire is evidently not to bolster up his theory, but to find out what is true. The character and spirit of such a man is a magnificent rebuke to those who prate of the demoralizing tendencies of science.

The first chapter in the first volume treats of the variations of domestic dogs and cats, and brings to light great numbers of interesting facts showing the extent and nature of variability in these animals, which however, as would naturally be expected from their well known habits of life, is much less noticeable in the feline than in the canine race. The variations of the horse and ass under domestication, as reported in the second chapter, are still more to the point. Pigs, cattle, sheep, and goats are only briefly treated of; rabbits receive rather more attention; but the emphasis of Mr. Darwin's investigation is on the fifth and sixth chapters, which are devoted entirely to the variability of pigeons. The attention which our author has bestowed upon this subject has been most unstinted in its quantity, and in its quality of the highest. The results are commensurate with the earnestness and conscientiousness of his search. From the common rock-pigeon it is plain that there have descended varieties so unlike each other and so unlike their first progenitor, that, in a state of nature, they would be classed at once as different species, In the seventh and eighth chapters the variations of several races of birds are briefly indicated, also the variations of hive-bees and silk-moths. Chapters nine, ten, and eleven are devoted to the variations of different plants. From the nature of the first volume it will be seen that its worth must depend almost entirely on. Darwin's qualities as an observer. It contains very little theory. And if we are not

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mistaken, it is generally agreed that, however defective Darwin's general theory may be, we have no more indefatigable and accurate observer of the naked facts of animal and vegetable life than he. And the facts which are presented show an enormous amount of variation. The implied argument of the volume, of course, is: If man, with his limited command of the material, can bring about such changes by favoring this and frowning upon that peculiarity, what may not natural selection have done, with every secret in its hand and unlimited time in which to operate.

The second volume begins with a chapter on inheritance, in which the wonderful and complex character of this apparently simple fact is set forth with great ability. Then comes a chapter on that most wonderful group of facts and relations, for which Darwin uses the terms Reversion, or Atavism. He will probably find in Dr. Holmes an ardent admirer of this portion of his book, and in "The Guardian Angel," a true although fictitious illustration. The chapters on crossing and interbreeding, on hybridism, advantages and disadvantages of changed conditions of life, are full of interesting matter. The twentieth and twenty-first chapters show us what man can do, by favoring variations, towards the formation of new breeds. The laws of use and disuse are seen to play a most important part in variation. The chapter on correlated variability brings together many important observations which show how certain parts of various animal and vegetable organizations always, or nearly always, vary simultaneously. Sometimes the nature of this connection can be seen; but in the majority of cases it is hidden. From this law it follows that with our domesticated animals and plants varieties rarely or never differ from each other by some single character alone.

But that portion of these volumes which will probably excite the most attention and give rise to the greatest amount of discussion, is contained in the twenty-seventh chapter of the second volume, where the author sets forth his "Provisional Theory of Pagenesis." This theory is very intimately connected with all the preceding chapters in the second volume, being a bold attempt to account for the phenomena of inheritance, variability, and reversion. The theory is not entirely new. Buffon, Bonnet, Owen, and more explicitly Herbert Spencer, have hinted at the same thing. Darwin himself does not advance it with much assurance, but, seeing a great deal in its favor, gives it for what it is worth. The theory implies that the whole organization, in the sense of every separate cell, reproduces itself; that ovules and pollen-grains, the fertilized seed or egg, as well as buds, consist of a multitude of germs thrown off from each separate atom of the organization. Whether this theory is justifiable O. not, it is certain that if it can be established it will throw a great deal of light on many subjects that are now dark enough. The work closes with an excellent summary of its general contents, and with an earnest appeal for a fair hearing and an equally earnest caveat with reference to the question, whether every variation has been specially preordained. Its publication by Orange Judd & Co. will probably introduce it into many quarters where it would not go if published as a purely scientific work. But such it is. It has no practical intent whatever, and yet it is a book which every intelligent farmer would do well to read; for if it does not furnish him with practical suggestions, it can but make him a more reverent worker in view of the great laws in which his humblest offices take root and grow.

The Book of Evergreens. A practical Treatise on the Coniferæ or Cone-bearing plants. By JOSIAH HOOPES, member of the Academy of Natural Sciences of Philadelphia. Illustrated. (Orange Judd & Company, 245 Broadway.) Mr. Hoopes has performed a difficult and useful task in a very satisfactory manner. Although there are many foreign works devoted to the coniferæ there has not been, up to this time, any American book on the subject giving descriptions of all the different species and varieties that will endure the climate of the Middle States. This want has now been supplied, and Mr. Hoopes deserves the thanks of his countrymen for having put before them a great deal of valuable information in a compact and handy shape. The introduction contains and brief but sufficient account of the botanical structure and classification of the order coniferæ, and also a statement of the different authors who have written books exclusively devoted to the subject. The first chapter—misprinted the second—is devoted to the very important matter of soil and planting, and contians excellent practical advice. Mr. Hoopes agrees with Downing in rejecting Loudon's Advice to plant evergreens in the autumn, as unsuited to our climate; but he also disagrees with Downing in his recommendation of early spring planting. After quoting Downing's remarks, Mr.