January 31, 19 18] 



NATURE 



423 



vided combined nitrogen for manure and explo- 

 sives in sufficient amounts to enable Germany to 

 continue the war. 



A last chapter, written for this edition by Sir 

 Henry Rew, gives a somewhat more optimistic 

 forecast, based on more recent and detailed statis- 

 tics, of the possibility of extending the world's 

 wheat supply without the introduction of any new 

 f.ictor, such as cheap nitrogenous manure made 

 fiom the atmosphere. 



Of the vital interest and importance of the 

 problem at the present time there can be no two 

 opinions. The book should be read by everyone. 

 For some years the world's wheat crop has barely 

 sufficed for the world's consumption. With the 

 restriction of labour, manures, etc., by the war, 

 a world's wheat shortage may confidently be ex- 

 pected. What this would mean to us is shown by 

 the fact that wheat prV>vides more than 30 per 

 cent, of the energy of the national food budget, 

 and as much as 60 per cent, in certain classes. 

 Every possible effort should, therefore, be made to 

 increase wheat production. 



The Corn Production Act will no doubt in- 

 cicase the area. To increase the crop per acre is, 

 as Sir William Crookes suggests, a problem for 

 the laboratory. But there are many possibilities 

 beyond the synthesis of cheap nitrogenous 

 manures. In the first place, the amount of farm- 

 yard manure produced annually in the United 

 Kingdom is probably not far from 50 million tons, 

 containing about 250,000 tons of nitrogen. Half 

 of this is certainly lost, through the imperfect 

 methods of making and storing in common use. 

 If the loss could be reduced -by only 10 per cent, 

 the saving of nitrogen would be equivalent to a 

 normal dressing of sulphate of ammonia over the 

 whole wheat area of the United Kingdom. 



But manurial nitrogen is by no means the only 

 factor which limits wheat production. It has been 

 estimated that fungoid diseases on the average 

 depress the world's wheat crop by about 30 f)er 

 •cent. Biffen's work on the inheritance of im- 

 munity to rust has opened the door for improve- 

 ment in this direction. Experience gained with the 

 first rust-immune variety to get into general cul- 

 tivation — " Little Joss " — suggests that immunity 

 to rust in this country is able to increase the yield 

 by about 10 per cent. In. other countries im- 

 munity to other diseases would probably be still 

 more effective. 



Heaven has shown, too, that even when the 

 total crop is limited it is possible to select varieties 

 which give an abnormally high proportion of grain 

 to straw. This method of selection, which has so 

 far been applied only to barley, appears likely to 

 increase grain production by at least 10 per cent, 

 without increasing the drain upon the soil. 



Notwithstanding these and possibly other fac- 

 tors which may increase yield per acre, there is 

 no doubt that in the main a cheap and plentiful 

 supply of nitrogenous manure, combined with the 

 spread of knowledee as to its proper use, would 

 do more than anything- else to increase the world's 

 wheat production. With this in mind perhaps it is- 

 not too much to hope that Lord Rhondda will use 

 NO. 2518, VOL. 100] 



his power as capitalist and organiser to ensure 

 that the fixation of atmospheric nitrogen shall 

 have a fair chance of succeeding both commer- 

 cially and scientifically. T. B. W. 



THE PROBLEM OF HUMAN INSTINCT. 

 (i) The Psychology of War. By Dr. John T. 



MacCurdy. Pp. xi-l-68. (London: William 



Heinemann, 1917.) Price 2s. 6d. net. 

 (2) Instinct in Man : A Contributioti to the Psy- 



chology of Education. By Dr. J. Drever. 



Pp. x-t-281. (Cambridge: At the University 



Press, 1917.) Price 95. net. 



THE study of instinct as a factor in human 

 nature is a modern, even a contemporary, 

 development. The philosophers of the seventeenth 

 and eighteenth centuries wrote much about the 

 passions and the inclinations and the, appjetites, by 

 which they meant the irrational impulses which 

 form the baser animal nature, up)on which, as they 

 thought, the rational nature is superposed as a 

 spiritual endowment. The modern treatment of 

 the problem, however, is the outcome of the enor- 

 mous advance of the biological sciences in the 

 latter half of the nineteenth century in the work 

 of Darwin and his successors. Particular atten- 

 tion is being focussed on the study to-day. The 

 great world-war, with the deliberate destruction of 

 ! accumulated wealth on a gigantic scale, and the 

 devotion to death and mutilation of a whole gene- 

 ration, is so manifestly irrational that we are 

 driven, perforce, to seek the meaning and cause of 

 war in instinct as opposed to reason, in a primi- 

 tive nature consisting of impulses and cravings im- 

 perfectly controlled by intellect. 



(i) The two books before us deal with this 

 problem of instinct in man from very different 

 points of view. The small book of Dr. MacCurdy 

 is of the nature of an exhortation called forth by 

 the special circumstances of the day. The idea 

 that underlies it is that there is a striking analogy 

 between abnormal psychology, which reveals the 

 havoc wrought in the individual mind by the loss 

 of control over repressed complexes, and the psy- 

 chology of nations at war. The suggestion is 

 that there may be a psychiatry for social, as there 

 is for individual, disintegration of personality. 



(2) Dr. Drever's main interest is the applica- 

 tion of the theory of human instinct to educa- 

 tional theory and practice. The modern problem 

 of instinct is threefold — philosophical, psycho- 

 logical, and biological. The philosophical problem 

 concerns the cognitive aspect of instinct, and 

 centres round the theory of Bergson. Instinct, 

 in Bergson's view, is a mode of knowing, intuitive 

 in character, different in kind, and divergent in 

 orientation from the mode of knowing which we 

 name intelligence. Dr. Drever, without definitely 

 rejecting this view, thinks that the problem can be 

 solved by the adoption of a very simple formula. 

 This is that instinct is knowledge at the percep- 

 tual level, intelligence being conceptual. But, 

 useful as such a distinction may be for provisional 



