334 



NATURE 



[November io, 192 i 



Fruits of the Tropics and Subtropics. 



Manual of Tropical and Subtropical Fruits: 

 Excluding the Banana, Coconut, Pineapple, 

 Citrus Fruits, Olive and Fig. By W. Popenoe. 

 (The Rural Manuals.) Pp. xv + 474 + 24 

 plates. (New York : The Macmillan Co. ; 

 London: Macmillan and Co., Ltd., 1920.) 

 305. net. 



A CONSIDERABLE literature on the more 

 important fruits of tropical nnd subtropical 

 countries exists, much of it in the form of bul- 

 letins or articles in journals which are not easily 

 accessible to all who require them. A volume in 

 which all the more valuable information so widely 

 distributed had been collected would have proved 

 a boon to many. Such a purpose Mr. Popenoe's 

 manual has, in a large measure, fulfilled. But 

 the work is far from being a mere compilation. 

 The author has drawn freely on the writings of 

 others, as he admits, but his wide knowledge of 

 the subject has enabled him to select critically 

 from the material at his disposal, and having 

 travelled' extensively in tropical and subtropical 

 regions as agricultural explorer for the United 

 States Department of Agriculture, as well as 

 having had practical qpcperience in fruit-culture 

 in California and Florida, he has produced a 

 volume based largely on his own observations 

 and experiments. Certain well-known fruits, as 

 pointed out on the title-page, have been excluded 

 for the reason that they have been already dealt 

 with in other volumes, while the term "fruits," as 

 understood in the volume under notice, does not 

 include nuts. 



The work is divided into sixteen chapters, the 

 first being an excellent article on the outlook for 

 tropical fruit. Then follow chapters on the fol- 

 lowing and related fruits : The avocado, the 

 mango, the annonaceous fruits, the date, the 

 papaya, the loquat, fruits of the myrtle family, 

 the litchi, the sapotaceous fruits, the kaki, the 

 pomegranate and the jujube, the mangosteen, the 

 breadfruit, and miscellaneous fruits, among which 

 are included the durian, caramjbola, tamarind, and 

 tree-tomato. Before the index there is a brief 

 bibliography, and in addition to the twenty-four 

 half-tone plates there are sixty-two line-drawings 

 in the text. The book is well printed and in 

 every way a worthy companion to the many ex- 

 cellent works comprising "The Rural Manuals," 

 edited by Dr. L. H. Bailey. We have no doubt 

 that it will be regarded, as it deserves to be, as 

 one of the standard books on tropical and sub- 

 tropical fruits. 



There are probably few fruits of much im- 

 portance, in addition to the six named on the 

 NO. 2715, VOL. 108] 



title-page, that are not included in the work, 

 though in some cases the information given about 

 them is necessarily very meagre. We observe 

 that none of the Cucurbitaceae is mentioned. 

 Most of the fruits of this family are apparently 

 outside the scope of the volume, though 

 Acanthosicyos horrida, the narras or 'nara, a 

 native of south-west tropical Africa, is one that 

 might have been included, for it appears to have 

 qualities that would render it an invaluable plant 

 for hot, dry, sandy regions, where very little 

 vegetation of any kind is found. The late Prof. 

 H. H. W. Pearson said of it in the Kew Bid- 

 letin, 1907, p. 344: " For about four months in 

 the year the fruits and seeds render the 

 Hottentots independent of other sources of food, 

 and to some extent of water also." 



Our Bookshelf. 



How to Teach Agriculture: A Book of Methods 

 in this Subject. By Prof. Ashley V. Storm and 

 Dr. Kary C. Davis. Pp. vii + 434. (London : 

 J. B. Lippincott Company, 192 1.) 125. 6d. net. 

 Drs. Stokm and D.'^vis have produced a book 

 entirely for the teacher; they develop some inter- 

 esting ideas and make a number of suggestions 

 which cannot fail to be helpful. The book con- 

 tains an interesting chapter on teaching through 

 charts, slides, and tilms, which could be read with 

 advantage by many agricultural teachers in this 

 country. The authors state that the use of films 

 as a means of teaching is rapidly gaining ground 

 in America. The expense of the projecting 

 machine is being reduced by the manufacture of 

 smaller and less costly models, while the expense 

 of the films is being lessened by more economical 

 methods of manufacture. Teachers and producers 

 are co-operating in making films that are actually, 

 and not merely ostensibly, educational, while the 

 inefficiency of the film service is being overcome 

 by the development of co-operation between 

 schools, colleges, and commercial and teachers* 

 organisations. 



The Electrical Transmission of Photographs. By 

 M. J. Martin. Pp. xi-r 136. (London : Sir Isaac 

 Pitman and .Sons, Ltd., 1921.) 65. net. 

 Although the transmission of photographs over 

 telegraph circuits may still be said to be in the 

 experimental stage, a number of processes have 

 been developed to a considerable extent, and 

 already pictures are sent over the London-Paris 

 and other lines to a limited extent in illustrated 

 journalism. The author summarises the work of 

 various inventors in this field, and the processes 

 described include those depending on the action 

 of light on selenium, and those in which a stylus 

 travels over a metallic image. Full instructions 

 are given for the construction of an experimental 

 equipment, and a chapter is included referring 

 brieflv to the wireless actuation of such apparatus. 



