Page:Science vol. 5.djvu/173

 mpABT so, 1885.]

��r stndy by the younger generation gf com- ing geologists, who have yet lo begin iheir acqaaintance with tbe atmcture of that vast region.

The geological map is a very welcome coiitri- buiioii lo our records of the phj-sical history of British North America. It measures the great progress made in western explorations since Sir William L<^an and Professor James Hall pre- pared the well-known map of Canada and the Dorth-eastem United States in l^tliG. and pre- sents an authorized graphio digest of the mauy sketch-maps and reports that have been pub- lished since that time. Much of the work is, of course, broadly generalized, and is doubt- less open to serious changes ; but the great fixtures iif the country are well represented, and in the west show a very clear continuation northward of those found within our territory, . with the addition of certain peculiarities proh- ibly dependent on a more extensive glaciation i s greater recent depression in the north- D area. The vast breadth of the horizontal K>Z0ic and tertiary strata of the plains, iween the undetermined confusion of the Ar- lean on the east, and the paleozoic moun- __ Uin ranges on the west, gives a character to ~this region that finds no close parallel in other parts of the world.

The ' general map of part of the north-west territories,' prepared at ihe Dominion lands- office at Ottawa, may be recalled while men- tioning the geological sheets. It rcpi-esents the region nortliward from our boundary, be- tween Hudson Bay and the front range of the Rocky Slountains, on the same scale of forty tniica to an inch, and, in the latest edition we have seen, is corrected to March, \S8'^- Its topographic detail, especially as regards the ragged outlines of the numerous lakes drained by the Nelson River, is decidediy greater than tiiat of the later geological map. Iktth are, we presiitne, in great part only approximations to the exact truth ; but, unless the former is imagi- naiy in its details, the uninitiated can hardly

Iandcrstand why it was not used as the base- ma/p for the geological coloring. I'erhaps pbere is need of better co-ordination of gov- ipunent work in Canada as well at* with us. h

��mOODACE'S VEGETABLE HISTOLOGY.

��X'r to the time of the translation of Sachs's text-book of botany into English, something

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�� ��over ten years ago, comparatively little interest was felt in vegetable histology and physiologj' in this country : and no modern English trea- tise on the subject, of any importance, existed. The direction given to the work of students by Sachs's book was soon manifested by a demand for less comprehensive text-books, adapted to the use of more elementary classes ; and Thomi;, Prantl, Bessey, and Kellerman have successively appeared as the result of this demand.

While the space given to physiological sub- jects in the earlier editions of Gray was doubt- less adequate when these were prepared, the revision of the book required that these subjects should be treated far more comprehensively than was possible within the limits of the original work : hence the appearance of a sepaiate volume allotted to tbem.

For convenience the author has divided this volume into two parts, devoted respectively to histology- and physiolt^. The first of these has recently come from the press, and sustains the high character of the work of which it forms a part.

An important feature of this volume is the concise introduction, in which the histological appbanccs and methods most frequently used are brought together for discussion, the writ- er's long experience as a laboratory teacher making this condensed account of much prac- tical value to the student. Following this ore chapters on the cell and its parts ; modified cells, and the tissues they compose; Che struc- ture and development of the root, stem, and leaf of phaenogams ; and the structure and development of the flower, fruit, and seed.

These subjects are treated in much the same manner as in several of the later text-books, though an unusual degree of facility in group- ing the topics in a logical manner is shown ; and no opportunity is lost of indicating the practical aspects of the subject under consid- eration.

While this jiart maintains the conservatism with regard to Insufficiently suljstautiated theo- ries that characterizes the earlier volume of the text-book, it is well abreast of tbe times in a branch of liotany which is admittedly- in a far from settled condition. A marked im- provement on the usual classification of tissues is observable in the adoption of a smaller number of types, the limits of which are capa- ble of more precise definition, while the treat- ment of their derivatives is probably the best logical classification of tissues, based largely on the admirable work of IlaberlandC, forma
 * x>ssiblG on a morphological basis. A physio-

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