REVIEWS 677 



particular species. The index is good, extending as it does to twenty-nine pages 

 with double columns ; even so one looks in vain in it for such a well-known 

 name as Lucerne, although over the description of this plant {Medicago sativa) the 

 British name is given as an alternative to the American name Alfalfa. 



The growing interest in and importance of the economic aspects of botany, 

 together with the reasonable price of the book, make it very welcome at this 

 time. 



W. S. 



Fnngi and Disease in Plants. An Introduction to the Diseases of Field and 

 Plantation Crops, especially those of India and the East. By E. J. 

 Butler, M.B.,F.L.S. [Pp. vi + 547, with 5 coloured plates and 205 other 

 figures.] (Calcutta and Simla : Thacker, Spink & Co., 1918. Price 

 Rs. 15= 10s.) 



Mr. Butler as Imperial Mycologist at the Agricultural Research Institute at 

 Pusa has had exceptional opportunities for studying parasitic fungi, especially from 

 the economic standpoint, and it need scarcely be said that the present work, whilst 

 primarily supplying a great need of the Indian student and grower, has more than 

 local value. It is indeed a fact that not a few of the diseases prevalent in the 

 temperate regions are caused by organisms specifically identical with those of 

 Europe. 



Rather more than a quarter of the text is devoted to general topics such as the 

 diverse types of parasitic fungi, their habits and life history, and their relation to 

 disease and control. Special mention may be made of those sections dealing with 

 specialisation of parasitism and the relations of host to parasite, both of which are 

 useful summaries of somewhat neglected but economically important aspects. 

 The behaviour of specialised races has for the grower a significance that can 

 scarcely be overestimated. The occurrence of " bridging" species, such as barley 

 for the rust of wheat to oats, may be commoner than is supposed, and the 

 possibility of wild species and especially of natural hybrids playing this role must not 

 be overlooked. 



The effect of environment on immunity is a subject with which the author also 

 deals'. Observations have shown that resistance to disease may vary with the local 

 conditions of soil and climate which probably react upon the anatomical structure 

 or physiological condition of the plant. It is suggested that several features primarily 

 regarded as transpiration checks, by rendering the lodgment of spores difficult or 

 impeding penetration, probably play an important part in decreasing susceptibility 

 to disease As such characters are extremely plastic, this may explain in part the 

 marked differences, as regards immunity, of the same variety when grown in 

 different localities. 



Though in many cases the only method of control for these fungal pests is by 

 the selection of immune strains, the effectiveness of the excellent work which has 

 been done in this direction by breeders is largely defeated by our ignorance as to 

 the causes of deterioration and the environmental factors which tend toward 



increased resistance. 



None the less valuable, though less interesting to the general reader, is the 

 second part, where some two hundred diseases are described which attack the 

 field and plantation crops of India. These are arranged in reference to the 

 host plants, which are grouped under such headings as Cereals ; Pulse crops ; 

 Dye, Drug, and Spice crops, etc. 



The diseases of the Sugar Cane, Tea, Rubber, and Coffee receive a chapter 



44 



