92 PLANT PHYSIOLOGY 



zero and the maximum affect the rate of growth in a variety of ways, as they 

 do also the final form of the plant. 



1. 28, for and KNY (1902) read KNY (1901), ILTIS (1903), BUSGEN (1903). 



305, 1. 9, after way read they do not elongate their internodes, however, 

 but form a greater number of them than when exposed to light ; many trees 

 also in absence of light show a precocious unfolding of the buds of the following 

 year; 



306, 1. 5, for 102 read 90 



1. 19-29, for The varied behaviour . . . means, read The varied behaviour 

 of the individual organs of a plant, as well as of different species, shows indeed 

 that in etiolation we are dealing with a stimulatory effect of darkening which 

 leads to the most diverse results according to conditions. In the first place, 

 there is always an alteration in the normal correlations among the organs ; but 

 it cannot be said with certainty whether the primary effect of darkening in 

 Dicotyledons consists in an inhibition of the unfolding of the leaves, the result 

 of which is a more vigorous elongation of the internodes, or whether, conversely, 

 stem growth is accelerated in the first instance, the leaves in consequence 

 remaining small. BEHRENS (1905) has shown in the case of hemp that darken- 

 ing of the internodes only does not induce any super-elongation in them. In 

 other cases, however, it has been shown that leaves in darkness may reach their 

 normal size, if they be well nourished by removal of all buds, thus saving them 

 from competition with these axes (JosT, 1895), or if vigorous elongation of 

 these be prevented by suitable ligatures (PALLADIN, 1890), or if the leaves 

 continue to develop after isolation (RiEHM, 1905). 



I. 52, for and generally speaking read and plants which are accustomed to 

 live in light of high intensity, such as Sempervivum, become etiolated in light 

 which is still quite bright (WIESNER, 1893) ; generally speaking, we may say that 



307, 1. 18 P. 308, 1. 18, for Experimentally it may be shown . . . altera- 

 tion in colour, read We can cite only a few out of the numerous examples which 

 are known as to the formative influence of light of varied intensity. (Then read 

 1. 51 P. 310, 1. 26.) 



308, 1. 18, before Etiolated plants read We shall take another opportunity of 

 studying the effect of the intensity of light on flower formation ; meanwhile, 

 we may note that, in addition to the form, the colour of plants is greatly influ- 

 enced by light. 



II. 43-50, for Similarly ... for solution, read Further, the formation of 

 the red pigment (anthocyan) is often, but not invariably, dependent on the 

 presence of light (OVERTON, 1899 : KUHLBORN, 1904). Since the development 

 of this pigment is affected in manifold ways by different substances (KATic, 

 1905), it is conceivable that the light induces relatively simple chemical effects 

 in this case as in that of chlorophyll. 



1- 53 f r produced . . . exposed to read correlated with 

 1. 54, for in older stages read is the adult form. 



310, 11. 27-8, for We shall have ... we have still read Having discussed the 

 question of the intensity of light, we have now 



311, 1. i, after dorsiventrality read in mosses (NfiMEC, 1906). 



1. 8, after regions, read Closely related to dorsiventrality is the phenomenon 

 of heterotrophy (WIESNER, 1892), where secondary thickening and leaf forma- 

 tion are different in character on the upper and under sides of a dorsiventral shoot . 

 One especially remarkable case of heterotrophy is that of anisophylly, where the 

 leaves are of different size ; in extreme cases those arising on the upper side are 



