132 



MEMOIRS OF THE NEW YORK BOTANICAL GARDEN, 



long axes at right angles to the surface was noticeably lacking in 

 etiolated stems, in which no differentiation was to be seen except in 

 the development of one or two layers of smaller cells beneath the 

 epidermis. These cells contain a large number of globular clusters 



Fig. 88. Opuniia Opuntia. A, etiolated epidermis, surface view; /?, normal epi- 

 dermis, surface view. 



of crystals in the normal, which are not nearly so numerous in the 

 etiolated fronds. The outer walls of the epidermis were less 

 thickened in the etiolated. 



Osmunda cinnamomea L. 



Clumps of Osmunda brought into the dark room in April, 1900, 

 soon developed long straggling fronds thickly clothed with pale 

 hairs, with pinnae extended but not attaining a length in excess of 

 1.5 cm. The entire frond showed a distinct greenish tinge due to 

 the presence of a marked amount of chlorophyl. The outer tissues 

 including the epidermis were much less thickened than the normal, 

 the epidermal cells being notably elongated and containing chloro- 

 plasts. Functional stomata were present and contained many chlo- 

 roplasts. 



The parenchymatous tissues as in the normal showed some inter- 

 cellular spaces, but the walls were more or less wavy. The endo- 

 dermis (phloeoterma) was made up of smaller elements with less thick- 

 ened walls than in the normal. The pericyclic cells were not to be 

 distinguished from the sieve cells or the adjoining parenchyma. 

 The mass of tissue between the endodermis and metaxylem, usually 

 consisting of the pericycle, the parenchyma separating it from the 

 sieve tissue, and the parenchyma between the sieve tissue and the 

 metaxylem, was much thinner than in the normal, and it was not pos- 



