re mem I jc red by the cells, i.e., hulhicinationa. So, too. an abnormal lack of blood may es- hiitist the brain, may render a person mcapnble of cnrrj'ilig on mental proceaeea, and maj' even cause sncli a degree of hunger for oxygen ui the cells as in turn to produce irritation, and thus again hallucinations, followed by loss of memory. It is evident that Meynert regards many forms of mental disease as dependent u|>OD abnormal nutrition of the brain, either from hyperaemia or anaemia, — a position in which he by no means stands alone.
The description of physiological processes in the brain forms a fitting introduction to the study of its disorders. This division of the subject is to be taken up in the second volume, which will be eagerly looked for by those who have read the first. It will doubtless be as suggestive and original as this volume.
Meynert's book should be I'ead lioth by medical men and those interested in the prob- lems of psychology. Its technical parts will be of great service to those who study the minuleanatomy of the brain. Its physiological portion is of general interest, and will excite much notiee and comment. The facts and the conclusions are entitled to careful con- sideration, as they are the product of most mature and thorough tvork, even though the materialistic e.\planation is at times inade- quate. Meynert ia not to be placed in the ranks of Cierman philosophers. He does not grapple with the problems of psychology, as Lotzeor Wiindt have done; he writes from the stand-point of an alienist who seeks to resolve a mental process into its simplest elements, aud to detect in any given case of mental dis- oitler the particular element which is lacking. The explanation of the manner in which we acquire the idea of space is unsatisfactory (p. lliC). The causal relation is not sharply differentiated from the simple association of ideas by correlation in time (p. 164). Tbe time element in memory is not exhaustively discusseil. There are, doubtless, many trains of thought which are lai^ely the simple rising into consciousness of associated memory pic- tures. There are others which are not ti> be 80 easily accounted for, and to which no clew can be gained b\" a study of association fibres and of variations in the blood- supplj. To the psychologist, therefore, this wort will be of service only as a collection of facta in one department bearing upon his science, — facts which he must consider, but which by no means carry with them the explanation of the problems involved.
The work raises many ([Ueslions which the
��author does not attempt to answer. It would ^ perli.ips be unjust to demand from him .ilternpt, for he does not pretend to be writing as a psychologist. As a study of thought- mechanism, and as an inti'oducUon to a study of |)sychiatry, to which alone it lays claims, it is moie satisfactory than any work whiuh has ] I'ecently appeared.
��ENGINEERING GEOLOGY.
It is now generally admitted by mining and civil engineers that a knowledge of the princi- ples of practical geology is necessary for the I successful execution of those plans, depending j upon a correct conception and understanding j of the character of the surface of the eartii j and nnderlj'ing rocks, where engineering works, such OS bridges, railroads, canals, and even buildings, are to be constructed, and through I which, as in the case of rail road -tunnels anci ] mines, excavations are to be made.
The rapid progress which has been made in America during the past fifteen jears in prao- , tical geologj" has so completely absorbed the active profess ionalist, that none of our fleld- geolc^sts have found time to contribute a \ treatise to our literature such as Geifcie's Field. Penning'a Engineeriug, and Page's Economic geology, Burat's ' G^-ologie appliqnfi,' and the more recent work by Wagner, on 'The | relation of geolt^y to the engineering sciences.*
This last work is an elaborate and strictly 1 technical discussion of the application of prac- tical geology to tunnel-work and closely relat- I ed subjects. It contains superior plate (quarto ' pliotolithographs) and text illustrations, nod j will prove a work of great value, not only to ' professional field -geologists, but to students in practical geology and engineering, in deHu- ing some of the more u.seful and economically important applications of geologj- to engineer- ing work.
Some of the geological cross- sections in tlu text clearly illustrate the geotectonic principles referred to, but evidently perpetuate an abom- inable custom, long since abandoned by tht \ best American geologists, of exaggerating the ] vertical scale. The chapter on cxplorationfl I bj- boring is not up to the standard of our J home practice.
The practical esani|jlea cited from Wagaor'» I own ex|)ericncG aild much value and interest I to the work, which would be more useful tal
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