552 



SCIENCE. 



[N. S. Vol. XVII. No. 431. 



once occupied by a glacier is not stated; but 

 the hanging valleys join it only three or four 

 miles from the end of a large existing glacier 

 that is fed from the great snow reservoirs of 

 Kabru peak (24,015 feet). Hence Garwood's 

 explanation of these hanging valleys, involv- 

 ing so many hypothetical conditions — even 

 the capture of the headwaters of the assumed 

 east-flowing consequent being hypothetical in 

 a region of so complicated structure and of 

 so much dissection since the capture is sup- 

 posed to have taken place — can not at present 

 be advisedly accepted in place of the much 

 more probable explanation by glacial erosion. 

 The suggested explanation becomes all the 

 less satisfactory when it is perceived to de- 

 pend on two very doubtful postulates: (1) 

 the discordant relation of trunk and branch 

 valleys is assumed to result in part from a 

 supposed tilting of the drainage basin, yet no 

 proof of the principle underlying this assump- 

 tion is adduced from demonstrably tilted 

 basins in non-glaciated regions ; (2) the hang- 

 ing valleys are supposed to have been occupied 

 by glaciers that maintained a highly special- 

 ized and persistent relation to the valley 

 mouths; yet no examples are adduced to show 

 that this relation prevails in any region of 

 existing glaciers. 



One more point; Garwood argues for the 

 ' superior erosive power of water over ice,' 

 and this implies a misapprehension. It is 

 not essential to the glacial origin of hanging 

 valleys that the erosive power of ice should 

 he superior to that of water, but only that 

 the erosive worh of ice should he unlihe that 

 of water. How long a time the main glaciers 

 of a mountain range may have taken to scour 

 out their over-deepened main channels and 

 to leave the channels of smaller side glaciers 

 in the form of hanging valleys, and what 

 amount of work might have been accom- 

 plished by rivers in the same time and place, 

 no one yet knows. W. M. Davis. 



BOTANICAL HfOTES: 



TWO MORE BOTANICAL TEXT-BOOKS. 



Within a couple of months two books for 

 beginners in botany have been offered to the 



high schools of the country. The first is the 

 ' Introduction to Botany ' prepared by Pro- 

 fessor Stevens, of the University of Kansas, 

 and brought out by Heath & Company. It 

 is an attempt to introduce the beginner to 

 all departments of the science. Accordingly, 

 he is directed in his studies of seeds, seed- 

 lings, roots, buds, stems, leaves, growth, move- 

 ment, modified pai-ts, flowers, seed dispersal, 

 selected .spermatophytes (twenty-five kinds), 

 slime moulds, bacteria, yeasts, algse, fungi, 

 lichens, mosses, ferns, horsetails, adaptation to 

 environment, plants of different regions, plants 

 of past ages and classification. In all of these 

 topics the subject is treated comprehensively. 

 There is something of structure, morphology, 

 physiology, ecology, as well as- of the phi- 

 losophy of botany. Throughout the chapters 

 are scattered nearly two hundred observa- 

 tions and experiments to which the pupil's 

 attention is directed. Part II. of the book 

 describes the school herbarium, laboratory 

 eqtiipment, reagents and processes, and Part 

 III. is devoted to a pretty complete but not 

 very satisfactory glossary. A short ' flora ' 

 is appended to the volume, in which selected 

 spermatophytes are briefly described. The 

 treatment here is quite conservative, the old 

 nomenclature being strictly followed, although 

 the sequences of families are those of Engler. 



The book contains a great deal of valuable 

 matter, but it is open to the pedagogical criti- 

 cism of not separating the elementary and 

 fundamental from the advanced and more 

 technical aspects of the science. In the hands 

 of a wise and well-trained teacher it will be a 

 helpful book, but in too many cases its use 

 will leave the pupil in a more or less dazed 

 and confused state of mind, on account of the 

 fact that too many things have been brought 

 to his notice in the short time allotted to the 

 study. The author should prepare another 

 book in which only the elementary and funda- 

 mental parts of the subject are presented to 

 the beginner, and then the present work might 

 be enlarged and elaborated for the use of ad- 

 vanced students. 



The second book, with the suggestive title 

 ' Botany all the Year Hound,' is from the 

 hand of E. F. Andrews, of the High School 



