A Monograph of the Geniis Alar'ut. 25 



of length of the sporophyll extending gradually towards both ends. 

 The apex of the matured sporophyll is round and entire, and in 

 certain species a sterile portion may be left there. The general 

 statement given by Setchell^) about the development of the 

 sporophylls of Alaria holds good for the plants of this section 

 (Plate I, fig. 1). 



II. jNIetasoeia. Sporophylls of the species under this section 

 are thin and membranaceous or pa])yraceous at the beginning. If 

 the hair-tufts or the mucilage glands are present in the blade, 

 they are also well developed in tlie sporophylls. They are there- 

 fore functioning as a vegetative organ. Later on, they increase in 

 length by basipetal growth at a limited region near the petiole. 

 The newly formed portion is of much thicker texture, and in some 

 species is remarkably broader or narrower than the thin upper 

 part. The latter part wears away by degrees from the apex. 

 The thicker part becomes soriferous. The matured sporophylls 

 have generally certain portions of the thin and sterile foliole still 

 remaining at their upper end, but not unfrequently are entirely 

 free from it (Plate IX, fig. 1-3). 



When there is ample material showing various stages of 

 development of frond, the distinction above given is easily recog- 

 nizable. If, however, we have only very young or fully matui'cd 

 sporophylls in a specimen the matter is not so apparent. Very 

 frequently we meet with the fully matured sporophylls of the 

 Metasoria entirely free from the non- soriferous portions. In such 

 case one is apt to take the plant to belong to the Holosoria. 

 With but a few exceptions, the matured sporophylls of the Holo- 

 soria have broad and rounded apices with entire margins, while 



1) Setchell: On the Classificiition and Geograijliieal Distribnlion of the Laminariacoae, p 

 347. 



