54 



generalization holds faix"ly wall. Tor Easton the gereraliza- 

 tion hc7 l3, v/ith. three e:'MeptionP: the height j.adex is lovrer 

 than the other for the period "beginning May 8, "Itihough both' 

 indices have low val'aes, and th,is relation is reversed for the 

 periods "beginning June 22 and July 20, in spite of the fact 

 that both values are Ir^rrp-R^r. thenn o-ses. For P:M?-!nes£ A^ine 

 the gr'.-'phs show the values ol' ti.e h6isfi.t index at nigher than . 

 those of the other index for the periods ^sginning June 23, 

 July 7 and Jvlj £1, although both jndir;es are large for all 

 three periods. Otherv/ise these graphs agree with .the gener- 

 alization. 



The fact that the genflnl i p^a'^i 'r, gl-ron sir;'--- '-.olrls i r the 

 great majority of the cases here studied renders tl^e exceptions 

 od special interest vlth reference to the causal relations In- 

 volved. ■ I": maybe supposed, ssuming that the olants v/ere all 

 ali'-e at the begirming of all cultures and that no disturbing 

 influence was introduced by soil conditions, tin t -the periods 

 characterised by exceptions to this generalization should also 

 be characterized bi- some ;3ort of corresponding peculiarities 

 in the aerial environmental complexes. No^.-, ^ stu:Iy of the 



hharts for thii= exposed s■f'■^ *' fr-.Q >rings 'n-^ *"''"e follo:-;ing fact; 

 most of the £-v;eek periods for «iiich both plant values -are large 

 and yet the index of stem elongation is greater than tha^ 

 leaf-proiuct Incre'se, are characterized by " "^ 'ices of oil"- 

 shine intensity. Thj.? suggests that the plants ^f these cultures 

 experienced an acceleration in *:' ir rates of stem elongation 

 due to low ligi't 'ntensJt.y, iv + *-Hat they exhibite"! sr-.^ r '' 



the effects of inci^jient etiolation, Hhej see 3hcw a some- 



what increased, rate of ^ elongation and a somewhat decreased 



