DISEASE IN PLANTS 211 



themselves in health and disease, and how they react to external 

 conditions. The book has been compiled, the author tells us in the 

 preface, to meet the wants of a general public of agriculturists and 

 cultivators who wish to understand something of the nature of the 

 plants with which they are dealing, and of the maladies by which 

 these are attacked, but who have no desire to know minute details 

 of histology or the life-history of the fungi or insects that cause 

 disease. They are, he considers, in the position of the laity who 

 know the danger of being wholly ignorant of disease, but who 

 willingly leave expert knowledge to the professional man. It is 

 questionable how far Prof. Marshall Ward is right in condoning 

 such ignorance, for it is jnst the life-history of the disease-causing 

 organisms that the agriculturist requires to know, in order that he 

 may apply a suitable remedy at the right season. How can he 

 properly deal with rusted wheat, unless he knows that he must also 

 have an eye on the barberry ; and how is he to fight finger-and-toe 

 without understanding that the spores of Plasmodiophora remain in 

 the soil ready to begin their life-cycle again in some Brassica ? 



The first section of the book is entitled " Some Factors," and 

 gives an account of the life and development of the normal plant. 

 A discussion of the biology of the soil is included, and the bearing 

 of man's interference on cultivated plants as regards selection and 

 hybridization. The whole section is full of interest and suggestion, 

 though necessarily, from want of space, many points of interest are 

 merely indicated. 



The second and larger part of the book deals with disease, which 

 is defined as '' variations of functions in directions or to extents 

 which threaten the life of the plant," or, further, whatever causes 

 the "premature death of the plant." The Professor deals in turn 

 with the many risks the plant has to encounter before it reaches 

 maturity. The causes, the nature, and symptoms of disease are 

 passed in review, and a sketch is given of various malformations 

 and monstrosities. A printer's error on p. 245 makes " frugiferous " 

 bats responsible, in the tropics, for the bare condition of the 

 branches termed stag-head. The concluding chapters discuss the 

 nature of protoplasm, with special reference to the life and death of 

 plants. 



A short historical sketch of each subject adds greatly to the 

 interest of the work, and a carefully chosen bibhography is ap- 

 pended to each chapter ; but it seems a pity that all illustration 

 has been dispensed with, especially where description is necessarily 

 short. Professor Marshall Ward demands from his readers a fair 

 knowledge of botany in order to follow his arguments — a more 

 extensive knowledge than the ordinary cultivator possesses or is 

 likely to possess. Unless the Professor anticipates the day when — 

 if it may be allowed to travesty Plato — "agriculturists will be 

 philosophers, and philosophers will be agriculturists." A good 

 glossary of the technical terms used in the book would be of great 

 service, and might with advantage be added in a subsequent edition ; 

 so valuable a work should be made available to as large a circle of 



readers as possible. . ^ ^ 



A. ij. b. 



