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376 direction, producing results congeric with itself; hence, in the world of mechanical force, the series are complete, calculable, and demonstrative. But, obviously, other modes of activity are possible and probable to intelligent will. When acting in the organic instead of the mechanical world, though conforming still to a fundamental law of evolution, its results may not present series which shall be complete, calculable, and demonstrative, but incomplete, contingent, and suggestive. Such seems to be the character of the succession of animals and plants. The series, as an evolution, lacks its first terms; it presents regressions; it yields to the demands of physical correlations and ideal concepts; it betrays everywhere the activity of a force whose law is not that which dominates in the mechanical world.

"Mr. Spencer, in stating, in substance, that the efficient cause of evolution is a mode of the Unknowable, expresses our idea exactly in relegating this effect to a Power without the sphere of sensible things. But we differ from Mr. Spencer, toto cælo, in respect to his dogma of the Unknowable, holding that the causa causarum is revealed qualitatively to every rational being. The cause of evolution is therefore a mode or volition of the incomprehensible Mind."

Dr. Winchell's book will well repay perusal to those who are interested in the literature of the subject; and the addition of Barrande's argument against Darwinism, in the Appendix, will augment its value to scientific students.

present work is a supplement to Dr. Coues's admirable treatise entitled "Key to North American Birds," published in 1872, and contains matter originally intended for that volume, but which, owing to lack of space, was left for future publication. The first half of the book consists of eight chapters, in which the reader is told in an easy, entertaining way how to proceed in the collection, preparation, and preservation of birds. As you must "first catch your hare," the author very appropriately devotes the opening chapter to the subject of implements of capture, and, the gun being the chief of these, minute directions for guidance in its selection, care, and use, are given. A short chapter on the employment of the dog as an aid in collecting comes next; and is followed in Chapter III. with directions for general field-work, such as the time of year to make collections, the manner of approaching birds, their recovery after being wounded or killed, and how to dispose them for carriage homeward. The last section of this chapter, on "The Hygiene of Collectorship," contains a good many valuable suggestions that apply with equal force outside the business of bird-collecting. The fourth chapter deals with the subject of notes and labeling; the fifth is on instruments, materials, and fixtures, for preparing bird-skins; the sixth contains directions for skinning, and the preparation of skins; and the seventh treats of miscellaneous matters, such as the determination of sex and age, the study of osteological characters, and the collection and preservation of eggs and nests. The last chapter is on the care of a collection, and gives directions for the construction of cabinets, and the exclusion of insect pests. Drawn from the writer's own experience, which has been most varied and extensive, these instructions cannot fail to be of great use to those proposing the study of birds at first hand.

The second part of the book consists of a check-list of North American birds, intended to replace the one now in use, which, owing to the rapid advance of the science of ornithology, has become defective in many ways. A notable feature of the new list is the reduction of the number of genera, and especially of the number of species given in the old one, in accordance with the growing conviction that naturalists long ago got ahead of Nature in the formation of specific distinctions.

is an encouraging sign to the friends of progress that school-teachers are awakening to the necessity of scientific education. At the seventh annual meeting of