44 STRUCTURE AND LIFE-HISTORY OF HAY-SCENTED FERN. 
ning meristems have had a regular and orderly phylogenetic history (/ 
Bower, 1889). From the meristem a more or less homogeneous paren- 
chyma is directly derived. Very soon, however, farther differentiation 
occurs in the older parenchyma—the parts farthest removed from apical 
meristem. This differentiation has also been modified in course of time 
in response to the environment and the needs of the plant. But there is 
no reason to suppose that the changes in the meristem should have any 
direct relation to those in the older portions. Meristem develops from a 
growing point and its structure is influenced largely by the shape, size, 
number, and position of the initial cells. Mature tissues develop from 
below upward, and are shaped out of meristem in response to stimuli 
which come chiefly from the more mature cells. While this independence 
of meristem and mature tissues seems plainly indicated by a comparison 
of plants as they commonly occur, it is also capable of experimental inves- 
tigation. Some of the most promising material for this purpose would be 
in the genera Gleichenia (cf. Boodle, 1901) and Lindsaya (cf. Tansley and 
Lulham, 1902). But this is a subject which has yet to be followed out. 
Synonymy of generic names, and list of type species on strict Linnean priority. 
. Polypodium—Linneus, 1753—Type: P. lanceolatum (first species named.) 
. Dicksonia—L’ Heritier, 1788— Type: DV. culctta (or D arborescens). 
. Aspidium—Swartz, 1800—Type: A. articulatum (fide Underwood, 1899). 
. Dennstedtia—Bernhardi, 1800—Type: D. flaccida = Trichomenes flaccidum Forst. 
Nephrodium —Michaux—Date and type uncertain. Cf Underwood, 1899, p. 265.* 
. Sttobolium—Desvaux, 1827—Type: S. punctilobum. 
. Sttolobium—J. Smith, 1841—Type: S. punctilobum. 
. Litolobium—G. Kunze, 1848—Type: L. punctilobum. 
. Adectum—Link, 1841—Type: A. pelosiusculum. 
O ONY ANEW N 
*Cf. Davenport in Rhodora, 4 :158 ff., Aug. 1902. 
