SUPPLEMENT 157 



one for phosphoric acid, one for ammonium, and one for asparagin. While 

 the last-mentioned sensitivity is quite independent of the reaction of the culture 

 fluid, the two former sensitivities do exhibit such a dependence, inasmuch as 

 the response to phosphate takes place only in an acid solution, and to salts 

 of ammonium only in an alkaline solution. A certain ' tuning ' to the operative 

 factors is thus recognizable. Such ' tunings ' occur very frequently in lower 

 organisms, and that too without any recognizable cause, and often create 

 great difficulties in experimenting with them. 



1. 29, for strophic read topotactic 



1. 36, for jchemotactica read chemotactical 



1. 54, for The same result takes place read A similar explanation holds 



548, l.i, for yet read further ; after case insert also 



I. 23, for positively chemotactic in read chemotactically attracted to 



II. 24-5 , for after being . . . activity; read on entering these solutions, being 

 plasmolysed by them ; 



I. 50, after organisms read (for literature see PFEFFER, Phys. Ill, 358). 



549, 1. 3, for graduated read varied, 



II. 5-6, delete so that we may dismiss the subject in a sentence. 



I. 43, after same time raised read (also after the action of acids ; LOEB, 

 1906) 



II. 46-7, for exposed . . . intensity read in which the illumination is not 

 uniform 



1. 54, after indifferent condition, read This is one of those cases of changing 

 in ' tuning ' which have already been mentioned in speaking of chemotaxis of 

 Bacteria. 



550, 1. 40, after p. 472). read Much more doubtful still are the experiments 

 which have been carried out with drop cultures under the microscope, for 

 the actual distribution of light in these drops (CHMIELEWSKY, 1904) is quite 

 different from what the experimenters generally assume. 



I. 42, for strophic and apobatic read topotactic and phobic 



II. 44, 50, for apobatic read phobic 



551, 1. 5, for apobatic read phobic 



11. 6-10, for is apobatically . . . movements, read reacts phobically, for on 

 sudden darkening the colonies at once sink to the bottom. How this phobic 

 sensitivity is combined with topotactic sensitivity has yet to be explained. Only 

 after further investigations have been carried out will it be possible to say how 

 far light intensity and the direction of the rays affect phototactic movements. 



1. 19, for strophic read topotactic 



1. 20, for apobatic read phobic 



1. 38, for anode end of ... negative read anode, and this induces in the 

 organism negative 



552, 1. 20, for correspondnig read corresponding 



1. 53 P. 553, 1. 39, for It must be noted, . . . chloroplasts. read1\\\s, change 

 in position is often expressed externally on the leaf, for in the profile position 

 of the chloroplasts the leaf is a paler green. The profile position is assumed 

 in different plants under quite different light intensities ; in shade-loving 

 plants this intensity is low, and high in those which prefer bright sunlight. 

 Even in the cells of the same leaf differences manifest themselves ; thus the 

 chloroplasts in the lower layer of cells in Elodea take up the surface position in 

 light of higher intensity before those of the upper layer (MooRE, 1887). As 

 to the mode of origin of both positions, what has been said of Mesocarpus 

 holds good ; we have no certain knowledge whether the movements are 

 passive or active, although if the former, the phenomena would be more 

 easily explicable. 



