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THE AMEBIC AN NATURALIST [Vol. XLII 



the weight of the plant every ten days (Fig. 3). The 

 precise external conditions are not stated. 



In spite of the morphological complexity the autocataly- 

 tic reaction of growth is apparently not checked by inade- 

 quate supplies before the plant enters rather suddenly 

 upon the second phase. Here, from the present point of 

 view, we consider that the progress of growth is inter- 

 rupted, not by the primary physical-chemical causes, but 

 by secondary causes, presumably to be classed in the cate- 

 gory of stimulus and reaction. 



The numerous curves for the accumulation of different 

 organic and mineral constituents worked out for barley 









































































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and buckwheat at Geneva are of similar form, but do not 

 keep up the uniform rate of doubling so well as does the 

 curve of total fresh weight. 



In this connection the tall and dwarf forms of the same 

 plant present an interesting problem, and some experi- 

 ments have been started on sweet peas at Cambridge. 

 At the time of germination the seedlings weigh about 

 the same, whereas at the end of the season the weight of 

 a tall plant is many times that of a dwarf "cupid" grow- 

 ing alongside under similar conditions. Is the difference 

 due to a less vigorous autocatalysis in the dwarf form, 

 so that throughout its growth it takes a greater number 



