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the publication, by the Smithsonian Institution, nearly twenty-five years ago, of Harvey's "Nereis Boreali-Americana," there has been no work on United States algae, except formal lists, to which the student could refer. Dr. Farlow, who is one of the most eminent algologists in the country, has given us in this work a compact hand-book which will be of great service to the collector and student. In the introduction much interesting information is given regarding the distribution of species along the coast. Cape Cod forms a barrier to many species. Dr. Farlow says the difference between the flora of Massachusetts Bay and Buzzard's Bay, which are only a few miles apart, is greater than the difference between those of Massachusetts Bay and the Bay of Fundy. This difference is found to correspond precisely with what is known of the fauna. He speaks of the occurrence of southern species of sea-weeds in a small sheet of water near Gloucester, to which the sea has access during a small portion of each tide, and, in referring to the presence of certain northern species south, says, "It seems to be the rule that wherever the water is cold enough we meet Arctic species, and wherever it is warm enough we have Long Island species, regardless of the remoteness of localities where the species naturally abound, and, as far as we know, of the absence of currents to transport the spores." The book closes with an excellent bibliography, and fifteen plates containing fifty-seven figures.

second edition of this work was called for in 1879, the first having been speedily exhausted. A third edition, revised and enlarged, appeared last year. The nature of the work is expressed in its title. It makes no claim to completeness, but is offered as a guide to the student who desires to pursue this branch of study. The latest authorities have been followed, and free use has been made of standard works and journals treating upon the various subjects discussed. In the present edition there is appended a second part, consisting of finely executed plates for illustration of the text. The book may be commended as giving within reasonable limits an excellent account of chemical physiology and pathology.

reason why these authors are reviewed in company is probably because James Mill's system forms a sort of sequence to Hartley's, although this sequence is manifestly due more to the incidents of general intellectual growth in England than to any relation of discipleship between the authors.

The doctrine of association is shown to have first received a definite form at the hands of Hartley, although its inception as a principle is traced as far back as Aristotle. James Mill elaborated this doctrine, having at his command richer stores of science, but deprived it of some of those wider applications which later writers have adduced, and which were foreshadowed by the superior imagination of Hartley. To quote the author: "Let us first find a statement of the doctrine of association, in its very simplest terms. So far Hartley and James Mill are perfectly at one. We will take the definition given by the latter. 'Our ideas,' he says, 'spring up, or exist, in the order in which the sensations existed of which they are copies. This is the general law of the association of ideas, by which term, let it be remembered, nothing is here meant to be expressed but the order of occurrence.'"

On the whole, Hartley's conception of the doctrine was more physical than Mill's. He called it a theory of vibrations. The counterpart and development of this theory of vibrations, as explained by Hartley, is to be found, the author tells us, in the "neural tremors" described by G. H. Lewes and Dr. Maudsley.

A very simple and, perhaps, more