28 SOIL CONDITIONS AND PLANT GROWTH 



for new factors : synthesis is hardly attempted as yet. As 

 the factors are discovered attempts are made to give them 

 mathematical expression. Thus Liebig's Law of the Minimum 

 and F. F. Blackman's Limiting Factors are expressed mathe- 

 matically by Mitscherlich (p. 32) : V. H. Blackman ^ ex- 

 presses plant growth by the " compound interest law " : Miyake 

 (pp. 185 and i88)bringsammonification and nitrification within 

 the equation for autocatalytic actions ; and the modern agricul- 

 tural chemist is acquiring a taste for mathematical formulae 

 and constants unknown to the older generation of workers. 



This attempt to find mathematical expressions has been 

 resisted on two grounds : some suppose that phenomena 

 associated with life cannot in any case be expressed mathe- 

 matically and that nothing but a hollow appearance of agree- 

 ment can be obtained ; others consider that the mathematical 

 formula, if it is to hold at all, must be expressed in such 

 general terms as to become meaningless, e.g. many of the 

 actions going on in Nature can be expressed by exponential 

 equations if the terms are chosen with sufficient ingenuity. 

 The soil investigator, however, will be wise to secure all the 

 assistance he can, as the subject is complex, and it cuts across 

 the conventional divisions of science. 



In modern Experimental Stations the tendency is towards 

 team work. As an instance chosen because it is best known 

 to the writer : at the Rothamsted Experimental Station, 

 .instead of a number of isolated individuals, there is a body 

 of workers investigating the subject, each from his own special 

 point of view, but each fully cognisant of the work of the 

 others, and periodically submitting his results to discussion 

 by them. Separate workers investigate respectively the 

 bacteria, protozoa, fungi, algae, helminths, and insects of the 

 soil ; in addition physical and organic chemists are studying 

 the soil conditions, while others are concerned in the study of 

 the growing plant. A body of workers by harmonious co- 

 operation is able to make advances that would be impossible 

 for any single individual, however brilliant. 



1 Annals of Botany, 1919, 33, 353. 



