258 The American Naturalist. [March, 
ohnson’s ‘“ How Crops Grow.’’*—Twenty-two years ago the 
first edition of this book appeared, and immediately took a place among 
the necessary things for the student of plants. It gave, in compact 
form, an introduction to the chemical composition, structure, and 
physiology of the higher plants. It was the only American book 
which took note of the later work of the German investigations in 
plant anatomy and physiology. It was deservedly popular, and 
brought its author great credit. 
Now, after these years of trial, it is revised and reprinted, the new 
matter rendering necessary an entire resetting of the whole. In some 
parts the modernization of. the work has been quite notable, in others 
this is not as marked, while some portions have been allowed to remain 
as they were left when first written. In the chapter treating of the vola- 
tile part of plants, the changes are most marked and interesting. 
Here eight classes of ‘ proximate principles’’ are recognized, as follows: 
Water, the carbohydrates, the vegetable acids, the fats and oils, the 
albuminoid or protein bodies and ferments, the acids, the alkaloids, 
and the phosphorized substances. In the treatment of the carbhoy- 
drates, three sub-divisions are recognized, viz.: 
(a) Zhe Amyloses, having the formula (C,H,,O,)N, and including 
cellulose, starch, inulin, glycogen, the dextrine, and the gums (the lat- 
ter including the pectin bodies). 
(b) Zhe Glucoses, having the formula C,H,,O, and including levu- 
lose (fruit sugar), dextrose (grape sugar), galactose, mannose and 
arabinose 
(c) The Sucroses, having the formula, mostly, C,,H,,O,,>and includ- 
ing saccharose (cane sugar), maltose (malt sugar), lactose (milk sugar), ~ 
and raffinose. 
The vegetable acids fall into several groups, viz.: The fatty acids 
(acetic, butyric, etc.), and the oxyfatty acids (glycollic, lactic), both of 
which are monobasic, and the dibasic acids (oxalic, malic, tartaric, 
citric, etc.). The treatment of the protein bodies is likewise practi- 
cally new, to which nearly twice as many pages are given in the new > 
book as were assigned to it in the old one. 
Passing over much that is new in succeeding chapters, we take up the 
second part, devoted to the structure and physiology of the plant. 
2 How Crops Grow; a Treatise on the Chemical Composition, Structure, and Life of 
the Plant, for Students of Oe with numerous illustrations and tables of analyses» 
by Samuel W. Johnson, M. A., Professor of Theoretical and Agricultural Chemistry in 
the Sheffield Scientific School of A University ; Director of the Connecticut pie OES 
Experiment Station ; Member of the National face of Science, New Y : Orange 
Judd Company, 751 ee I2mo., pp: VI. an 

