— 19 — 



dark Chamber. At the end of a week the majority of the 

 leaves used had produced new growtbs, and these mostly 

 from the basal portion of the leaf. The first growth from 

 the leaf cells was of neither a pronounced rhizoid or proto- 

 nema nature ; the walls were colorless, the cross walls occasio- 

 nally perpendicular but more generally slightly oblique. With 

 exposure to Kght the filaments tended to a growth of a more 

 decided protonema nature, the cross walls were predominately 

 perpendicular in the abundant lateral branches, and quite 

 often in the main axes also, and the cells soon developed an 

 abundant Chlorophyll content, With time the walls of the 

 main axes turned brown , and the Chlorophyll content 

 disappeared, so that eventually the main axes, even though 

 exposed to the light, came to resemble rhizoids. With the 

 continued exposure to darkness the filaments soon became 

 brown; no chorophyll was formed, and the lateral branching 

 was very generally suppressed. In the cultures in the dark 

 no buds were formed, while in the light cultures the first 

 buds were noticed at the end of seven days, with the more 

 abundant production as growth continued. The buds originated 

 as side branches of the main axis soon after the filament 

 had grown from the leaf cell. In the further growth the 

 buds appeared at difterent points along the main axis and 

 were homologous with the lateral protonema branches. The 

 lateral branches might also in their turn give rise to buds 

 as lateral branches, and after six weeks an enormous number 

 of new plants was produced in this way. 



The protonema production occurred generally from the 

 cells of the the leaf base, either from the marginal cells or 

 from those of the lacerated base , more general than from 

 the cells in the interior of the leaf. Although protonema 

 originated from the cells removed from the periphery, no 

 distinct tendency to production from a certain side of the 

 leaf was noted. Part of the protonema would originate from 

 the contact surface and part from the free surface, sometimes 

 more from the contact surface, sometimes more from the 

 opposed surface, so that no constant effect of contact was 



2* 



