SUPPLEMENT 145 



of a fungal hypha. Further investigations are needed to clear up this point. 

 In regard to chemotropism also it is not known in what the primary act of 

 perception consists ; it is not known whether the stimulant must first of all 

 enter the plasma or whether bodies which do not so enter may act as stimulants 

 (PFEFFER, Phys.). 



1-33, for glucose read a glucose 



1- 35. f or or rea d an d 



11. 44-55, delete Starting from . . . 10 per cent. 



484, 11. 14-15, for [As to the . . . (1904).] read Chemotropic sensitivity occurs 

 also in roots as well as in the structures named ; this has been demonstrated 

 by SAMMET (1905) and LILIENFELD (1905). We cannot enter here into a 

 description of the substances which induce positive or negative curvature. 

 Since numerous bodies which are quite useless to the root induce positive 

 curvature, chemotropism in the root can have no great biological significance ; 

 it appears to play an important part, on the other hand, in the search for the 

 oogonia by the antheridia in Saprolegnia, and in the process of conjugation 

 in the Conjugatae. 



11. 23-54, f or MOLISCH'S method . . . root apex, read MOLISCH'S method 

 of experimentation does not indeed exclude stimulation as the result of unequal 

 atmospheric moisture (hydrotropism) (BENNET, 1904), still, after SAMMET'S 

 experiments (1905), there is no reason to doubt the existence of aerotropism. 

 SAMMET has placed roots and shoots on the one hand in a gaseous diffusion 

 flow, and on the other allowed gaseous currents to play on them unilaterally. 

 He found that roots always exhibited positive curvatures at first both to 

 oxygen, carbon-dioxide, and hydrogen, as well as to alcohol, ether, ammonia, 

 but these curvatures gradually become negative, for instance, with carbon- 

 dioxide. The shoots investigated show no curvatures when carbon- dioxide 

 and oxygen are used, but react negatively with the alcoholic vapour, &c. 

 The biological significance of the whole phenomenon is very doubtful ; 

 and as there are many discrepancies in the results obtained by MOLISCH, 

 BENNET, and SAMMET, a reinvestigation of the whole problem seems 

 desirable. 



MOLISCH noticed that aerotropic movements took place in roots after 

 decapitation, and SAMMET has confirmed this ; hence 



485, 1. 25, for in the growing zone, read no matter under what psychrometric 

 conditions the growing region be placed. 



1. 37, for lead . . . this case, read exhibit quite peculiar phenomena. 

 1. 46, after 1892 read and 1906 



486, l.i, for the saturation . . . sufficiently read there is always a gradient 

 in the concentration of the water vapour sufficient 



1. 22, after nature read (compare also FITTING, 1907). 



1. 45, for (Lecture XXXVIII). read These movements are certainly as 

 a rule not very conspicuous (NEWCOMBE, 1904), and hence, after their first 

 discovery by SACHS (1873), their existence was often denied, or they were 

 regarded as traumatotropic reactions. In the next lecture, however, we shall 

 get to know of unmistakable movements in response to contact in other 

 cases. 



487, Lecture XXXVIII is XXXVII of the 2nd German Edition. 

 1. 49, for 1903 a read 1903 



488, 11. 15-16, for Organographie, p. 610) ; read Organography, II, p. 426) ; 



489, 1. i, for curve read surface 



JOST K 



