254 



NATURE 



[November 4, 19 15 



and strict criticism would therefore be scarcely in 

 place. 



The book still serves what was doubtless its 

 first purpose — to excite curiosity regarding- the 

 nature and origin of plant varieties and to sug- 

 gest the enormous possibilities which still lie 

 before the plant breeder. Special reference might 

 have been made, in this connection, to tropical 

 products. Few, for example, have yet realised 

 what incalculable additions to the world's wealth 

 can yet be made by simple means. Rubber trees, 

 for instance, vary at least 200 per cent, in yield, 

 and it is with amazement that a plant-breeder 

 learns that the planters are content to sow, with- 

 out regard to breeding or quality, trees which 

 are to last many years. To a less degree this 

 is true of cocoanuts and many other objects of 

 tropical agriculture. The chapter on the vast 

 progress made in the teaching and investigation 

 of plant-breeding in the United States gives 

 evidence that this neglect will not long continue. 

 The practical hints might well be amplified. 

 Nothing is said, for example, of the method of 

 removing pollen by a water-jet, though this device 

 was, by the way, an American invention. More 

 curious is the silence on the subject of self-sterility, 

 a phenomenon which, whether as an obstacle or 

 a help, plays so large a part in the daily experi- 

 ence of every plant-breeder. 



The author's theoretical views are occasionally 

 novel. In particular, the statement is made that 

 individuality in plants is something quite distinct 

 from what it is in animals. This proposition might 

 with value be developed in an essay elucidating 

 some of the essential phenomena of variation, 

 but it is by no means a self-evident truth, to say 

 no more. From the long list of periodicals deal- 

 ing more or less with the subject, the Zeitschrift 

 fur Induktive Vererbungsund Abstammungslehre, 

 though by far the most important continental 

 journal, has by some accident been omitted. 



THE BRITISH RAINFALL ORGANISATION. 



Btitish Rainfall, 1914 : on the Distribution of 

 Rain in Space and Time over the British Isles 

 during the year 1914. By Dr. H. R. Mill and 

 C. Salter. 54th annual volume. Pp. 448. 

 (London: E. Stanford, Ltd., 1915.) Price los. 



THE volume contains the records of about 

 5500 observers in Great Britain and Ire- 

 land, and there are various articles associated with 

 rainfall. A paper on isomeric rainfall maps of 

 the British Isles was contributed by the director 

 of the British Rainfall Organisation to the Royal 

 Meteorological Society in November, 1914, and 

 the present volume contains a summary of the 

 NO. 2401, VOL. 96] 



I paper with the monthly and seasonal maps, A 



I frontispiece in colour shows the relation of the 



' rainfall in 1914 to the average of 1875-1909. The 



I distribution of rainfall in time is dealt with in 



various ways from the ordinary daily records. 



For the occurrence of rain days, droughts, and 



rain spells over the British Isles one hundred 



stations have been selected, distributed uniformly 



over the country. The number of rain days are 



given in a tabular form for each month, and 



graphically for the average 1892-1911 and for the 



year 1914. 



The year may be regarded as one of average 

 rainfall frequency in all parts of the country, with 

 g-enerally fewer rain days in the summer and more 

 in the winter than in a normal year. Absolute and 

 partial droughts are discussed ; the former is re- 

 presented by a period of more than fourteen con- 

 secutive days, no one of which is a rain day, while 

 a partial drought is a period of more than twenty- 

 eight consecutive days, the mean rainfall of which 

 does not exceed o"oi in. per day, A rain-spell is 

 practically the antithesis of an absolute drought, 

 and is a period of more than fourteen consecutive 

 days, every one of which is a rain day ; the 

 number of rain-spells in 1914 compared with the 

 average was slightly deficient. Monthly, yearly, 

 and seasonal rainfalls are given in a tabular form 

 and graphically ; for the British Isles as a whole 

 the rainfall in 1914 was 7 per cent, more than the 

 average. 



The Meteorological Office having introduced a 

 new system of units for the official records of 

 British meteorology, the British Rainfall Organ- 

 isation has fallen into line, and has adopted the 

 use of the millimetre as the unit for measuring 

 the depth of rain. The annual total rainfall for 

 all the stations is given both in millimetres and 

 inches, and this addition has involved the widen- 

 ing of the page of publication. The difficulty as 

 to a change in the definition of a rain day conse- 

 quent on the use of the metric units has been post- 

 poned to next year, and no alteration in this 

 respect has been introduced in the present volume. 

 Notwithstanding many difficulties arising 

 directly and indirectly from the war, the rainfall 

 work has been carried out in all its details, 

 although the exigencies of the times have caused 

 some reduction of staff, and naturally the income 

 has dropped. Greater stress is expected next 

 year, and a hope is expressed that the rainfall 

 records, so essential to the good of the country, 

 will not suffer. An effort is being made to aug- 

 ment the voluntary funds by the aid of which 

 the work is carried on, but public funds are not 

 at present available, and the Treasury has decided 

 that in the circumstances no action can be taken, 



