BOOKS RECEIVED. 



711 



continued fraction h + \ + j &c, the author observes : " Hence 

 mathematical statements became read into the subject with which botany 

 has nothing whatever to do." Might not something similar be said of 

 log-spirals ? Indeed he admits that the log-spiral theory is put forward 

 solely as a mathematical conception, admittedly gratuitously introduced 

 into plant-morphology. 



" Ennemis et Amis des Arbres Frui tiers, de la Vigne et du Rosier." 

 Tar C. Duval. 8vo., 504 pp. (Bailliere et Fils, Paris.) 3s. del 



This little book, which contains some five hundred pages, will be found 

 by fruit-growers who are able to read French to be of considerable use, 

 though, fortunately, many of the pests mentioned are not natives of this 

 country. The arrangement of the matter is unusual, but in many ways 

 it is very practical. The book is divided into three parts. The first deals 

 with fruit trees in alphabetical order, and, under the headings of roots, 

 stems, leaves, and flowers, gives the names of the various pests which 

 infest those parts of the tree. After the name of each pest is given a 

 number, under which it is described in Part II. A useful calendar 

 is provided, showing the insects &c. which may be expected to be found in 

 the course of each month. The second part of this work is devoted to 

 descriptions of the different enemies of the various trees, their life-histories, 

 and the best methods of destroying them. They are given in the follow- 

 ing order : insects (including mites), small animals, snails, slugs, fungi, 

 other vegetable parasites, ailments due to defects in the soil, unseasonable 

 weather, &c. To each pest is given a different number, which corresponds 

 with that given after each when mentioned in Part I. It would have 

 been simpler, however, in Part I. to have referred to the pages on which 

 the description of the insect &c. would be found. A few words on the 

 anatomy and classification of insects are given at the commencement of 

 Part II. Under the heading of defects in the soil, it is stated that the 

 disease known as chlorosis is caused by excess of lime, or coldness, 

 dampness, or poorness of the soil. Watering with sulphate cf iron is 

 recommended as a remedy ; in the case of vines this treatment should be 

 continued several years in succession. The dropping of immature fruit 

 it said to be due to a want of lime in the soil, and that the best remedies 

 are chemical manures, stable manure, or chalk. The cracking of fruit is 

 caused by excessive moisture following drought ; if the soil has become 

 unusually dry, watering should be done carefully. The third and last 

 part is given up entirely to the " friends of fruit trees, vines, and roses." 

 One is glad to see that a list is given of about fifty different kinds of 

 birds which are of use to the fruit-grower, though the number described 

 is nothing like that number. It has been so much the fashion on the 

 Continent to destroy all the small birds that it is pleasant to see that so 

 many are recognised as friends. This book, like so many that are 

 published in France, is issued with merely a paper cover, so that anyone 

 who intends to use it as a book of reference will have to get it bound, or 

 it would soon come to pieces. There are a fair number of illustrations, 

 but many of them are very poor, however ; the book is not an expensive 

 one (3s. 9c7. in English money), so that really good figures could hardly 

 be expected. 



