belongs to the work now under notice, will be found in the author's habit of pleading in behalf of the facts of successive development of plan, which no one denies, as if this were in all respects equivalent to the production of specific forms by the mere constant action of natural laws. "It was a dream," he says, "of the dawn of true geology that fresh creations of animals were connected with the great physical revolutions of the surface, but this idea is passing away. It is becoming more and more clear, that organic progress depended not by any means wholly or immediately upon external circumstances, but in a great measure on time." The conclusion would be that the huge struthious birds which have left their footprints on the sands of the Permian, or the Trias, were developed into higher forms, and passed into the mammals which lie higher up in the geologic scale. The zoological aspects of the work draw their strength, if they have any, mainly from quarters into which most intelligent readers can follow its author. But many will find much difficulty in dealing with the author's appeal to embryology, as full of facts in support of his theories. The embryo of the highest types of life, he holds, assumes at different stages of its growth the form of the well-marked characteristic of the embryo of the types below it. Believing that the highest types were once no more than simple gelatinous masses, and that there was a time when all possible life existed thus, he avers that even the mammal repeats its whole past history during the period of its embryonic development. Were we all as watchful as we ought to be in the study of the embryology of the mammalia, we would assuredly be rewarded, we are told, with glimpses of the stages through which during long intervals we have passed up to our present attainments. Each man would have plain proof that the whole human race once lay in a polype, in a starfish, in an oyster-shell, under the wing-cases of a beetle (of Carabaus Hercules we suppose), in a fish, in a reptile, in a bird, in a monkey, from which last stage it was quite easy to become a man! The testimony in behalf of his "argument" claimed from embryology lies, however, where most of his other strong points lie, even in his own imagination. Von Baer, Agassiz, and others, have clearly shown that the plan of the Creator extends to the embryonic forms as well as to the mature, and that these are developed in different ways according as they belong to one zoological class or another. Indeed this is distinctly intimated in the Bible itself. The care of God is traced to the very beginning of life, and the unchanging thought in the divine plan is recognized. In thy book," says the psalmist, "all my members were แ written, when as yet there was none of them." Looked at in this light, and in the view of man's discovery of the thoughts of God in it, the whole passage is highly suggestive:— "For thou hast possessed my reins: Thou hast covered me in my mother's womb. I will praise thee; for I am fearfully and wonderfully made: My substance was not hid from thee, when I was made in secret, And curiously wrought in the lowest parts of the earth. Thine eyes did see my substance, yet being unperfect: And in thy book all my members were written, Which in continuance were fashioned, when as yet there was none of them. How great is the sum of them! If I should count them they are more than the sand: When I awake I am still with thee."—(Ps. cxxxix. 13–18.) Much prominence is given to the embryological view of this question by Professor Huxley in his "Man's Place in Nature." He refers to the important labours of foreign embryologists in this field, without indicating the very important difference of opinion which exists with regard to certain phenomena. Without following the line of remark pursued by him on this subject, which, though complete in so far as it goes, is yet defective in not giving prominence to the fact that there are stages in the development of the embryo which have not been well ascertained, it may be useful to point out one or two things bearing on the question under notice. Chiefly during the last thirty years, the researches of the zoologist have been carried into fields of fresh interest. The study of embryology has opened up new paths, as richly suggestive of the presence, the wisdom, power, and love of the Creator as the most complicated structural features of the full grown animal are. Von Baer, Van Beneden, Vogt, Agassiz, and others, have found that the growth of the embryo, in animals in whose fully developed structure evidences of four distinct plans have been observed, have forms of evolution peculiar to each. Thus the embryo of the Radiata differs in its evolution from that of the Mollusca, which again is unlike that of the Articulata-the Articulata differing, moreover, from that of the Vertebrata. And here again we meet with the presence of mind, of plan, of intelligent method, in fields remote from the common eye. The same God everywhere works. His care reaches to the remotest point in the life of his creatures. His tender mercies are over all his works. The discoveries of Von Baer have added elements of great additional weight to the system of classification proposed by Cuvier, which is based on the recognition of four great types of structure-evidences of four distinct plans-among animals. Cuvier's conclusions were arrived at by a very wide comparison of species, after minute examination of individual structure. Von Baer enters the same field guided by a very different thought, and his researches harmonize with those of Cuvier. The study of the embryonic forms of animals results in the recognition of four plans, just as the study of their bodies from the point of view of comparative anatomy had done. The importance of this in Natural Theology cannot be too highly estimated. Von Baer recognizes four types of embryonic development:-1st. The Peripheric Type, in which the organization radiates from one focus to the periphery, or circumference; and when the embryo has distinct parts, these are formed ring-like around the central disc, and send their branches into the rays which reach to the circumference. This he styles "Evolutio radiata." 2nd. The Longitudinal Type, which, extending throughout the whole department Articulata, has, as a chief characteristic, the receiving organs standing at one end, and the discharging organs at another. The nervous system in this type very soon becomes prominently developed. But this in some varieties more than others. Thus sensibility and irritability differ in different groups of the series. In spiders they are greater than in worms; in insects greater than in crustacea. The development is styled "Evolutio gemmina"-because it is carried on along two sides of a central axis in the production of identical parts, which close up along a line opposite the axis. 3rd. The Massive Type, or Evolutio contorta-so called from the development taking place in the production of masses curved around a disc. This answers to the molluscan forms of life. 4th. The Doubly Symmetrical Type, which is characteristic of the embryo of all the orders of the Vertebrata. "The development produces identical parts, arising on both sides of an axis, growing upwards and downwards, and shutting up along two lines, so that the inner layer of the germ is inclosed below, and the upper layer above. The embryos of these animals have a dorsal chord, dorsal plates, ventral plates, a nervous tube, and branchial fissures." This is styled "Evolutio bigemma." But not only is this true of the department Vertebrata, it is found that the different orders have embryos charac teristic of each. Monotremes differ from Marsupials, those again from true Carnivora, and the Flesh-eaters from the Ruminants. Some years ago the scientific world was startled by the announce VOL. I. 4 A |