HISTORICAL REVIEW 



21 



Impressions from the sense-organs, and directing the several 

 movements." 



This work of Darwin seems to have been set aside by 

 some of the most prominent Investigators of the day and 

 has even to this time not received recognition In accord 

 with Its importance. Loeb does not mention It at all. 

 Sachs refers to It In the following terms (1887, p. 689): 

 " In such experiments with roots not only Is great precau- 

 tion necessary, but also the experience of years and an 

 extensive knowledge of vegetable physiology, to avoid 

 falling Into errors, as did Charles Darwin and his son 

 Francis, who, on the basis of experiments which were 

 unskilfully made and Improperly explained, came to the 

 conclusion, as wonderful as it was sensational, that the 

 growing-point of the root, like the brain of an animal, 

 dominates the various movements in the root." The very 

 point which Sachs rejects has however been confirmed by 

 Pfeffer (1894), Czapek (1895, p. 244), Rothert (1894, p. 3), 

 and others. Czapek's experiment bearing on this point 

 is ingenious and convincing. He forced the apex of radicles 





n 



Fig. I. I. Seedlings of Lupinus albus (smaller size). The seedling (A) has 

 been removed from the klinostat after the apex is fixed in the glass cap k, and after 

 twenty-four hours has curved so as to place itself parallel with the perpendicular 

 line shown by the arrow. After Czapek, from Pfeffer (1906). 



II. Seedlings of Setaria italica. The roots have been cut away down to the 

 rudiments w, the cotyledon [plumule] fixed in the glass tube a, and the seedling is 

 then placed horizontally. In A the hypocotyl has curved through 180°, and at 

 B has formed a complete coil. (Twice enlarged). After Darwin, from Pfeffer 

 (1906). 



while being rotated on a clinostat to grow into small bent 

 tubes of glass closed at one end. When the seedlings were 



