1908] 



BARNES &> LAND— CU PULE OF MARCH ANTIA 



405 



bors to outgrow them, so that they can soon be located by the depres- 

 sion of the surface, as well as by their form and size (p, fig. 3). The 

 depression, however, is not always well marked at this stage (cf. 

 fig. 5). The contents, too, are sometimes distinctive, a glandular 

 appearance being not infrequently noticeable; but as all the cells 

 l hereabouts are rich in protoplasm, this feature is not very striking. 

 The next step in development is the prolongation of one or more 



Fig. 7. — Two gemmiparous cells 

 elongated; I, young air chambers; /, /, 

 as in fig. 2. 



Fig. 8. — Further elongation and first 

 division of gemmiparous cells (p, />); in/ 

 longitudinal division; w, rim cells. 



of the gemmiparous cells into papillae (p, figs. 5, 6), and simultane- 

 ously the further upgrowth of the cells at the rim of the depression, 

 and first on the posterior margin (w, figs. 4, 5, 6). The free ends of 

 the papillose extensions quickly enlarge (figs. 7, 8) and doubtless 

 secrete some of the mucus in which the whole apical region is envel- 

 oped. Certain of the cells that form the rim divide obliquely (w, 

 figs. 4, 8). Probably the cells thus cut off are the primordia of the 

 thin lobes, which arc so marked a feature of the mature cupule; for 

 even in this early condition the rim becomes scalloped. 



After some further extension and enlargement, the gemmiparous 



