1908] 



BARNES &* LAND—CUPULE OF MARCHANTIA 



403 



notions of its homology with an air chamber, as we now proceed to 

 show. 



Abundant fresh material was at hand from thrifty plants of 

 Marchantia polymorpha, grown under glass by Mr. John Cook, the 

 skilful gardener of the department, who has taken much pains with 

 the cultivation of Hepaticae. Being transferred directly from the 



Fig. 3. — Gemmiparous area (/>) out- 

 grown by adjacent tissues. 



Fig. 4. — Stage nearly as in -fig. 3; 

 w, a rim cell cutting off the primordium 

 of a lobe of the cupule. 



cultures to the fixing fluids, the material was in exceptionally good 

 condition. 



Our figures show usually only the cell walls, the perfectly preserved 

 contents being omitted for the sake of clearness. Mitotic figures 

 were common, showing that the cells were in active growth. The 

 figures are of longitudinal sections, except fig. 13, are all drawn to 

 the same scale, and having been reduced one-half are now magnified 

 about 625 diameters. 



Longitudinal sections through the apex of gemmiferous plants 

 show, as near to the apical cell as the third segment, a differentiation 

 in the cells which are to form the gemmiparous area. Instead of 



