70 DEVELOPMENT AND HEREDITY. 



of the experiment is taken from a review i of Dr. Max 

 Scholtz's "paper on the nutation of the flower-stalk 

 in poppies and of the terminal shoots in Virginian 

 creeper. In both cases, the nutation is dependent 

 on the action of gravity, but has nothing to do with 

 the weight of the bud. In the case of poppies, the 

 downward curvature of the stalk takes place, with 

 sufficient force to lift a weight equal to twice that 

 of the flower-bud. If, however, the flower-bud be 

 removed, there is no longer any nutation ; the stalk 

 straightens itself. Vochting had already shown that 

 this is the case even if the amputated bud be tied 

 on again with thread. Dr. Max Scholtz further 

 states that, if a weight three times as heavy as the 

 bud is substituted for it, the stalk still straightens 

 itself and lifts up the weight. The state of the case, 

 then, is this : the upper part of the flower-stalk, dur- 

 ing a certain stage of its growth, is, in a high degree, 

 positively geotropic if it remains in connection with 

 a developing flower-bud, but not otherwise. The 

 author has further succeeded in determining the 

 exact part of the flower-bud which governs the geo- 

 tropism of the stalk. If the pistil is excised, nuta- 

 tion ceases, the stalk becoming negatively geotropic ; 

 but if all the other whorls of the flower are removed 



1 "New Contributions to the Biology of Plants," by D. H. S., Nat- 

 ure, September 15, 1892. ' 



