95^^^ AGRICULTURAL BOTANY, CHEMISTRY AXD PHYSIOLOGY OF PLANTS 



and the character of the root system is the same as in the preceding period. 

 The growth of the roots continued after the end of anthesis (when that of 

 the parts above groimd had ceased) as was ascertained from the observa- 

 tions of daily development of the root sji'stem by means of " observation 

 boxes " fitted with a glass wall. In the roots of flax there is a character- 

 istic winding observed in all the periods of life of the plant. The influence 

 of the depth of the seeds on the development of the root system of flax was 

 not found so clear and decisive as in the case of oats, but differences do exist 

 and must be taken into account in the researches. 



Studies of Root IvEngth under natural Conditions of Develop- 

 ment. — After reviewing the results arrived at by different investigators 

 of the root system, with a view to co-ordinating them, the writer describes 

 his own experiments carried out on a plot of the experimental field of the 

 Agronomic Institute of Moscow. He adopted the method of Deile;rain. 

 cultivation on inclined planes, modifying and completing it. He carried 

 out cultivation : (i) on a natural soil profile by digging a trench' 281.6 cm. 

 wide, and 176 cm deep, with bottom rising gradually towards the surface 

 of the field so that the plants were not on banked-up soil, as at Grignon, but 

 at field level : (2) cultivation on inclined planes, utilising for this purpose 

 the embanking work carried out 40 years ago for water-regulation pur- 

 poses. The length of the roots was measured at 3 different times, nam.ely : 

 i) germination, 2) flowering, 3) fructification. The results are summed 

 up in Table II, which also indicates the differences in the length of the 

 roots in successive periods in order to bring out more clearly the behaviour 

 of the root system of each plant. 



On analysing the data of Table II, it is seen that, in their first period 

 of life, the plants under investigation had already developed their root sys- 

 tem to such an extent as to penetrate deeper layers than those subject to 

 ordinary tillage. 



Starting from the idea of aerial vegetative levels, the writer gives the 

 following scheme of underground vegetative levels. 



The first level, down to 44 cm. depth from the surface, comprises the 

 root system of short-rooted plants, chieflj^ weeds, annual or biennial, the 

 typical representatives of which are, for instance : Capsella Bttrsa-pastoris, 

 Viola tricolor, Thlaspi arvense and Berteroa incana ; among cultivated 

 plants, buckwheat belongs to this group. 



The second level (between 44 and 88 cm. depth) is occupied by the root 

 ends of short-rooted cultivated plants, for instance : Sinapis, Linum, Vicia 

 saliva, Pisum arvense, etc. 



The third level (88,139, 174 cm.) comprises the root ends of long-root- 

 ed cultivated plants : Vicia villosa, Panicum miliaceum, Avena saliva and 

 Solanum luberosum, etc. 



Next there is a fourth level, comprising onlj' the root ends of long-root- 

 ed wild herbaceous plants, as for instance : Vicia Cracca, Polentilla ar gen- 

 tea, Tanacetum vulgare, etc. 



Finall}^ the deepest level found lies between 261 and 352 cm.; it con- 



