Variability as a Nutritional Phenomenon. 51/ 



plants and sickly branches tend to fluctuate in tlie oppo- 

 site direction. 



But "individual strength" points clearly to nutrition, 

 if we use this word in its widest sense and especially if 

 we make it include the better opportunity which a i)lant 

 has of being nourished, as when it has plenty of room 

 and plenty of light, and so forth. 



If we view the whole field of nutritional phenomena 

 and that of fluctuating variability-^ they appear to inter- 

 lock only to a certain extent. Many statistical inquiries 

 point as little in the direction of such a connection, as 

 the excessively vigorous or feeble growth of weeds and 

 cultivated plants under extreme conditions seem to point 

 to it. But indications that the two phenomena are in fact 

 connected, are by no means lacking. Goebel, for ex- 

 ample, observed that in Agrimonia Eupatoriuni the lower, 

 best nourished, flowers of the inflorescence had many 

 more stamens than the upper more feebly nourished 

 ones.- In the sugar-beet the capsules on the lower part 

 of the stem contain many seeds ; those on the upper part 

 and on the small lateral branches contain few, and often 

 only one. Many varietal characters answer the require- 

 ments of the gardener only when they are on strong in- 

 dividuals; if the plants are weak they are developed 

 either too little or not at all (e. g. Cclosia cristata). 



We must make it our business therefore, on the one 

 hand, to study the results of increased and diminished 

 nutrition, by statistical methods; and on the otlier to 

 deal with the conditions affecting the different groups 

 of individuals, when studying Quetelet's curves. 



An inquiry of this kind will at any rate have one 



^ See C. Fruwirth, Die Zikhtuug dcr landicirthschaftlichcn Cul- 

 turpHancen, igoi. 



^ GoEBEL, Bot. Zcitung, 1882, p. 357- 



