774 



SCIENCE. 



[N. S. Vol. II. No. 49. 



culiarities in the grouping and arrangement of 

 crystals and the structure of minerals. Other 

 physical properties such as cleavage, fracture, 

 hardness, specific gravity, color, luster, etc., 

 are treated briefly in the fourth chapter. In 

 the fifth the chemical characters of minerals are 

 discussed, and in the sixth the use of the blow- 

 pipe and simple means of making chemical tests. 



The seventh chapter, taking up about one- 

 half of the volume, is devoted to a description 

 of the mineral species. Of course only the 

 common and important ones are considered, the 

 chief features by means of which each mineral 

 may be recognized being clearly brought out and 

 its crystallization or structure well illustrated. 

 The uses to which the mineral may be put are 

 also given. The classification adopted is not the 

 usual and more scientific chemical one, where 

 the minerals are grouped according to the acid 

 radicals, for example, the sulphates as one group, 

 the carbonates as another, etc., but the minerals 

 are grouped according to the different metals 

 which they contain. In each case there is first 

 given a brief account of the metal and its uses, 

 followed by a description of the common 

 minerals containing it. The silicates, owing to 

 their complexity and the fact that, with few ex- 

 ceptions, they are not economically useful as 

 ores of the metals, are treated in a group by 

 themselves. 



In the last chapter some simple rules for the 

 identification of minerals by means of their 

 physical properties are given. 



The book is one which certainly will be found 

 very useful, and a careful study of it in connec- 

 tiou with a collection of mineral specimens will 

 form an excellent foundation in the science. 

 S. L. Penfield. 



The Elements of Botany. By Francis Darwin. 



Cambridge, University Press. 1894. Mac- 



millan &Co., New York. $1.60. Cambridge 



Natural Science Manuals. 



It is a common habit of teachers and writers 

 of botany to select a typical plant for study, 

 one which shall illustrate within itself all the 

 fundamental structures and life processes of 

 plants. Francis Darwin in the volume before us 

 takes up the problem at the other end: that is, 

 he selects typical structures and jihenomeua and 



studies each in some common plant which seems 

 to show a given feature in its most undisguised 

 state or condition. This is e^adently the most 

 natural method for the beginner, for it selects 

 those emphatic types of plants which yield the 

 fundamental lessons with the least desultory 

 effort on the part of the student. There is uo 

 single plant which illustrates all the phenomena 

 of plant life and structure with equal clearness, 

 and the student who seeks to draw all his 

 typical examples fi'om the one species is likely 

 to obtain only a faint impression of all those 

 processes and anatomies which are more or less 

 obscure in his specimen. But if the student is 

 allowed to range for his material, or rather, if 

 a wide range of material is placed before him, 

 he is impressed rather with general and repre- 

 sentative phenomena than ynth. dissection and 

 specialization. 



It seems to me, therefore, that the plan of 

 Mr. Darwin's book is excellent. He illustrates 

 the fundamental conceptions of the cell, of re- 

 production, of nutrition aud of fermentation, 

 by the yeast-plant, spirogyra, tradescantia, 

 elodea and elder pith ; of reserve materials and 

 germination by the bean and gourd, tubers of 

 potato and artichoke and bulb of tulip ; of 

 the phenomena and structures of roots, by 

 broad-bean ; stem tissue by sunflower, and the 

 like. The book is a reprint of lecture notes, 

 and this accounts for its brevity and directness 

 of style, and also, no doubt, for some inelegancies 

 of construction. The book is wholly elementary 

 and is divided into fourteen chapters to accom- 

 modate ' the work of fourteen mornings,' which 

 comprises the scheme of botanical lectures 

 in the course in elementary biology given at 

 Cambridge, England, to medical students. The 

 book also has an appendix comprising directions 

 for fourteen laboratory exercises to correspond 

 with the class-room instruction. A particularly 

 worthy feature of the book is the steadfastness 

 with which it adheres to the discussion of the 

 particular type in hand, thereby omitting the 

 modifications and exceptions which so often 

 confuse the mind of the beginner. 



It seems to be necessary to take issue with 

 Mr. Darwin's interpretation of the morphology 

 of the rosaceous flower. He designates the 

 flower-cup, in which the cherry ovary sits, and 



