Part 67

On Species, =24=, 305, 1857.

Classification of Mammals, =35=, 65, 1863; =37=, 157, 1864.

Cephalization, =22=, 14, 1856; 36, =1=, 321, 440, 1863; =37=, 10, 157, 184, 1864; =41=, 163, 1866; =12=, 245, 1876.

Homologies of insectean and crustacean types, =36=, 233, 1863; =47=, 325, 1894.

Origin of life, =41=, 389, 1866.

Relations of death to life in nature, =34=, 316, 1862.

Of the above, the articles on cephalization as a fundamental principle in the development of the system of animal life have attracted much attention. The evidence from comparative anatomy, paleontology, and embryology alike supports the view that advance in the ontogenetic as well as in the phylogenetic stages is correlated with the unequal growth of the cephalic region as compared with the rest of the body. Dana shows that this principle holds good for all groups of animals. His homologies of the limbs of arthropods and vertebrates, however, do not accord with more modern views.

Other papers on the same and allied topics were published by Dana in other periodicals. His most conspicuous zoological works, however, are his reports on the Zoophytes and Crustacea of the United States Exploring Expedition, 1837–1842. The former consists of 741 quarto pages and 61 folio plates, describing over 200 new species, while the Crustacea report, in two volumes, has 1620 pages and 96 folio plates, with descriptions of about 500 new species. Each of these remains to-day as the most important contribution to the classification of the respective groups. The relationships of the species, genera and families were recognized with such remarkable judgment that Dana’s admirable system of classification has remained the basis for all subsequent work.

Dana’s critical reviews (=25=, 202, 321, 1858) of Agassiz’s “Contribution to the Natural History of the United States” are among the most interesting of his philosophical discussions concerning the relationships of animals as revealed by their structure, their embryology, and their geological history.

The remaining zoological articles in this series cover nearly the whole range of systematic zoology. Especially important are the articles by Verrill on coelenterates, echinoderms, worms and other invertebrates.

In the years following the publication of Darwin’s Origin of Species in 1859 occur many articles on the theory of natural selection. Some of the writers attack the theory, while others give it more or less enthusiastic support.

Experimental methods in solving biological problems were little used at this time, although a few articles of this nature appear in the Journal. Of these, a paper by W. C. Minor (35, 35, 1863) on natural and artificial fission in some annelids has considerable interest to-day.

Exploring Expeditions.

Of the important zoological expeditions the following may be selected as showing their influence on American Zoology:

The North Pacific Expedition, with William Stimpson as zoologist, returned in 1856 with much new information concerning the marine life of the coasts of Alaska and Japan and many new species of invertebrates.

In 1867–1869 the United States Coast Survey extended its explorations to include the deep sea marine life off the southeastern coasts and Gulf of Mexico under the leadership of Pourtales and Agassiz.

The Challenger explorations (1872–1876) added greatly to the knowledge of marine life off the American coast as well as in other parts of the world.

The explorations of the United States Fish Commission succeeded those of the Coast Survey in the collection of marine life off our coasts and in our fresh waters. These have continued since 1872 and have yielded most important results from both the scientific and economic standpoints.

Under the charge of Alexander Agassiz the Coast Survey Steamer “Blake,” in 1877 to 1880, was engaged in dredging operations in three cruises to various parts of the Atlantic. The U. S. Fish Commission Steamer “Albatross,” also in charge of Agassiz, made three expeditions in the tropical and other parts of the Pacific in the years from 1891 to 1905. The study of these collections has added greatly to our knowledge of systematic zoology and geographical distribution. The reports on some of the groups are still in course of preparation.

Period of Evolution, 1870–1890.

The time from 1870 to 1890 may be appropriately called the period of evolution, for although it commences eleven years after the publication of the Origin of Species, the importance of the natural selection theory was but slowly receiving general recognition. The hesitation in accepting this theory was due in no small degree to the opposition of Louis Agassiz. After the acceptance of evolution, although morphological and embryological studies continued as before, they were prosecuted with reference to their bearing on evolutionary problems.

Following closely the methods which had produced so much progress during the life of Agassiz, the field of zoology was now occupied by a new generation, among whom the pupils of Agassiz were the most prominent.

The teaching of biology at this time was also strongly influenced by Huxley, whose methods of conducting laboratory classes for elementary students were adopted in most of our large schools and colleges. This placed biology on the same plane with chemistry as a means for training in laboratory methods and discipline, with the added advantage that the subject of biology is much more intimately connected with the student’s everyday life and affairs.

This increasing demand for instruction in biology and the consequent necessity for more teachers brought an increasing number of investigators into this field.

Conspicuous in this period was the work of E. D. Cope, best known as a paleontologist, but whose work on the classification of the various groups of vertebrates stands preeminent, and whose philosophical essays on evolution had much influence on the evolutionary thought of the time. He was a staunch supporter of the Lamarckian doctrine. Alpheus Hyatt also maintained this theory, and brought together a great accumulation of facts in its support. He thereby contributed largely to our knowledge of comparative anatomy and embryology. A. S. Packard, whose publications cover a wide range of topics, was best known for his text-books of zoology and his manuals on insects.

W. K. Brooks was a leading morphologist and embryologist. S. F. Baird, for many years the head of the United States Fish Commission, was the foremost authority on fish and fisheries and is also noted for his work on reptiles, birds and mammals. The man of greatest influence, although by no means the greatest investigator, was C. O. Whitman. It is to him that we owe the inception of the Marine Biological Laboratory, the most potent influence in American zoology to-day; the organization of the American Morphological Society, the forerunner of the present American Society of Zoologists; and the establishment of the Journal of Morphology. G. B. Goode was distinguished for his work on fishes and for his writings on the history of science.

E. L. Mark, C. S. Minot, and Alexander Agassiz were acknowledged leaders in their special fields of research—Mark in invertebrate morphology and embryology, and Minot in vertebrate embryology, while Alexander Agassiz made many important discoveries in the systematic zoology and embryology of marine animals, and to him we owe in large measure our knowledge of the life in the oceans of nearly all parts of the world.

The knowledge of the representatives of the different divisions of the American fauna had now become sufficient to allow the publication of monographs on the various classes, orders and families. At this time also particular attention was given to the marine invertebrates of all groups.