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difference between the protonema grown in the dark and 

 those grown in the light, was that in the dark cultures the 

 cells were generally more elongated and devoid of Chloro- 

 phyll, and the branching less. The cell walls in both cases 

 were colorless. 



After about live weeks buds made their appearance, and 

 always as modifications of lateral protonema branches. Con- 

 trary to what has been described for all of the preceding 

 species the buds were formed in as great abundance in the 

 dark cultures as in the light. In the dark the buds did not 

 attain any considerable size on account of the lack of food 

 material, rarely reaching a length of 1 mm. The production 

 of buds in the dark is evidently explained from the nature 

 of the leaf. The lamellae and the lateral portions of the 

 leaf, since they give rise to no protonema are able to furnish 

 considerable food material which can be applied to the growth 

 of leafy shoots. These experiments show that in one case 

 at least light is not necessary for developing and unfolding 

 that slumbering "Anlage" of which Klebs 1 surmises the 

 existence. 



In order to determine if a correlation existed betiween 

 the lateral halves of the leaf and the costal region in the 

 production of protonema, the lateral halves of a series of 

 leaves were separated from the costal regions, and both 

 retained in culture. Under no conditions were the cells of 

 the laminae able to grow out into protonema, the cultures 

 being kept several months without any sign of growth. The 

 costal portions after the usual length of time showed a growth 

 of protonema in the ordinary way, only the number was 

 greatly reduced. The cells of the lamellae are not able to 

 grow out into protonema, neither when in connection with 

 the leaf nor when separated. The power of regeneration is 

 thus distinctly localized in the large cells of the costa lying at 

 the base of the outer lamellae. 



The whole plants which were kept under exactly the 



Biolog. Centralblatt 13:647. 1893. 



