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protonema was noted at the end of nearly three weeks. 

 As in the case of Bryum the 'first growth was neither 

 distinctly protonema nor rhizoid. Even in the cultures in 

 the light the main axis soon changed its cell-walls to a 

 we]l-marked brown, while the side branches continued as 

 distinctly protonema, with generally perpendicular cross-walls, 

 and an abundant Chlorophyll content. Buds were formed 

 very soon and consequently the protonema did not attain 

 any considerable size. In the cultures in the dark the 

 filaments remained long and occasionally branched, with 

 brown cell walls, oblique cross-walls and no Chlorophyll. 

 Buds were found after about three weeks, but these were 

 confined to the cultures which had been exposed to the 

 light. The buds originated in all cases as side branches of 

 the main protonema axes. 



The first experiments with the leaves showed that the 

 protonema originated exclusively from the larger cells lying 

 next the very base. None of the cells removed from the 

 periphery gave rise to protonema, but only those one side 

 of which was next the free lacerated base of the leaf. 

 Leaves were cut transversely, and also longitudinally and 

 all portions placed in conditions favorable for growth. The 

 apical half of the leaf gave rise to no protonema whatever^ 

 while the basal half only produced protonema from the 

 proximal end, with an origin the same as in the cases of 

 the whole leaves. The portions of the leaves which had 

 been split longitudinally also gave rise to protonema but 

 only from the base and not from the cells lying along the 

 cut margin. The power of regeneration is then located in 

 the basal cells of the leaf the same as in Barbula muralis. 

 The production of protonema is due to the Separation of 

 the leaves from the stem, since whole plants under exactly 

 the same conditions as the detached leaves produced no 

 protonema, and since when the y were cut and still allowed to 

 remain in connection with tbe stem no growth was called 

 forth. 



Essentially the same results were obtained with leaves 

 from a variety, except that the protonema originated exclu- 



