260 



SCIENCE. 



[N. S. Vol. I. No, 10 



accompanied by explanations that have 

 been prepared by trained observers who 

 have been all over the ground, examining 

 the forms of the surface as the expressions 

 of internal structures. From the sheets in 

 eastern Tennessee we may learn of the two 

 peneplains that there give local illustration 

 of wide-spread Appalachian forms. On the ' 

 Livingston sheet, Montana, there is a fine 

 illustration of one of the many extinct lake 

 basins now drained through a steep-walled 

 gorge, in a way so characteristic of the 

 northern Eocky Mountains. "With the 

 Placerville sheet, in the California Sierra, the 

 text tells of the reduction of the mountain 

 belt to gentle slopes before the eruption of 

 the great Neocene lava flows by which many 

 of the older valleys were broadly filled ; and 

 of the deep canyons cut by the displaced 

 rivers since the mountain belt has been up- 

 heaved with a westward slant. The plan 

 of liberal distribution of these folios ensures 

 that they will reach a wide variety of 

 readers. They will be welcomed by many 

 workers : students, teachers and investiga- 

 tors ; geographers, geologists and econo- 

 mists. 



geikie's great ice age. 



The third edition of this important work 

 has been lately issued (ISTew York, Apple- 

 ton, 1895). Although distinctly a geolog- 

 ical treatise, not written from the geograph- 

 ical point of view, it contains numerous 

 pages of physiographic interest, for many 

 glacial deposits are so young as still to pre- 

 serve essentially their constructional form ; 

 hence the account of moraines, drumlins, 

 rock-basins, and so on, are of immediate 

 geographical value. The general subject 

 of glacial erosion is hardly treated with the 

 fulness that the many discussions it has 

 given rise to would warrant ; and the ex- 

 planation of rock-basins does scanty justice 

 to the opinions of many Swiss geologists 

 who look on ice action as a secondary pro- 

 cess compared to a gentle warping of pre- 



existent valleys. The extract fi-om Wal- 

 lace's paper, defending the glacial excava- 

 tion of rock-basins, would imply that that 

 author was not acquainted with the numer- 

 ous lakes of dislocation in our western ter- 

 ritorj\ For American readers the two 

 chapters and the several maps by Cham- 

 berlin will prove attractive. 



W. M. Davis. 



Haevaed Univeesity. 



LABORATORY TEACHING OF LARGE 

 CLASSES— ZOOL OG Y. * 



If the large and increasing attendance at 

 our summer schools, and the publication of 

 many books and the reports made by those 

 dealing in scientific apparatus, can be taken 

 as an index, the amount of zoological teach- 

 ing is very rapidly increasing, and the con- 

 duction of large classes is a problem of con- 

 siderable importance. 



A class of college students numbering 

 twenty or twentj^-five, and conducted by 

 one officer, is a large class and, even with 

 a favorably equipped laboratory, is quite as 

 large as a single teacher should attempt to 

 carry. Of course, if a certain number of 

 assistants can be engaged, a larger number 

 of students can be directed, though this is 

 virtually the establishment of so many sub- 

 classes. 



One of the first conditions for successful 

 zoological instruction is that of immediate 

 environment. To crowd a score or more of 

 katabolic youth into a small, miserably- 

 lighted room, and compel them to breathe 

 the fumes of stale alcohol for two or three 

 hours, is to invite failure. Each student 

 should have a table to himself where there 

 is good light, and where he feels a certain 

 amount of proprietorship. It should be so 

 located that he is not tempted to carry on a 

 clandestine parasitism, or even a symbiotic 



* A paper read before the American Society of Nat- 

 uralists at the Baltimore meeting, Decemher 28, 

 1894. 



