956 AGRICULTURAT. BOTANY, CHEMISTRY AND PHYSIOLOGY OF PLANTS 



s^Tichronal constancy in the downward growth of the i"of)t system in in- 

 dividuals of the same pure line (of flax). 



The encjuiries of the writer into the length and weight of the root sys- 

 tems of oats, wheat and flax establish a dear and essential difference between 

 the length {and weight) in different forms of oats, spring wheat and flax. 



Table I summarises the most important results of the investigations 

 in relation to oats. 



The difference between root-length in the different varieties of oats 

 therefore varies greatly, with a maximum of about I metre (186.0-101.0 

 = 85 cm). Then, on comparing the root-lengths with the time of ripen- 

 ing, MoDESTOV notes an interesting fact : the longer the roots, the greater 

 the time required for ripening. In other words, the length of the roots 

 is proportional to the length of life of the plant. The author explains this 

 phenomenon by sa^dng that early varieties develop during the summer 



period when the moisture has not yet passed through the deeper strata of 

 the soil, and the roots, being able to find an adequate quantity of it, need 

 not lengthen out. This property, peculiar to early varieties (short-root 

 system), has been fixed by heredity and asserted itself in the cultivations 

 in boxes, i. e. in an environment different from the natural one. In the 

 varieties which ripen later, things happen differently : the plants develop 

 in the period when the moisture has already traversed the deepest strata, 



