178 



THE MAR All [ALES 



immediately surround the stoma. A section of the lamina presents an appearance 

 very much like that of Helmtnthostachys. Below the upper epidermis is a well- 

 developed palisade layer, while below this the spongy mesophyll has the characteristic 

 intercellular spaces found in the leaves of most of the higher plants. Danaa tricho- 

 manoides,3 very small species from Peru, has delicate membranaceous leaves, which 

 probably would show a much simpler structure than that of the coriaceous leaves 

 of the largei species. I), snitcnsis, a species from Porto Rico, which is in the herba- 

 rium of the British Museum, has adventitious buds developed at the leaf tip. 



cot 



1 10. 163. 



\. B. Two longitudinal sections of a young sporophyte of Kaulfussia. /' 

 tnd ird lcavi ; r 2 , second f">t. X20. 

 C. Stem apex. X180. D. Apex of third leaf. XiSo. 





THE VPICAL GROWTH OF THE ROOTS. 



I he earlier roots grow from a single initial cell, but this is later replaced by a 

 group of similar initials which, in the large roots, are very much like those described 

 tor the mot apex of Angiopteris (Koch I). Figure [62 shows a section of a root 

 from the young sporophyte which is somewhat transitional in charactei between the 

 form with a single definite initial cell and tin- largei root with its group of initials. 

 I he tell v, which is very much like the apical cell of the primal) loot, m.iv perhaps 

 still be considered as the single apical cell, but the ad jaunt segments are almost 

 equal in size to this, and it is clear that they contribute to the plerome cylinder of 

 the root as well as to the cortex and the root cap. 



In sections of large routs taken from the adult sporophyte, there is found at the 

 growing point not a single initial cell, but a group of apparently similar initial cells 

 somewhat wedge-shaped in longitudinal section and arranged in a radiating fashion. 

 \o single one of these can he clearly recognized as a primary initial cell. These 

 cells divide at intervals by longitudinal walls and from the bases additions are made 



