A Monograph of the Genus Aluria. -5 



generous enough to spare me two complete specimens of Alaria 

 valida Setch. et Kjellm. I am also indebted to Dr. W. Teanz- 

 scHELL, in charge of the Herbarium of the xVcademy of Science 

 of Petrograd, Prof. 0. Juel of the Botanical Museum of Upsala, 

 Prof. C. A. M. LiNDMAN of the Academy of Science of Stockholm, 

 Prof. Sv. MuKBECK of the Botanical ^^luseum of Lund, Prof. N. 

 Wille of the Botanical Museum of Christiania, and Prof. H. H. 

 Dixox of Trinity College, Dublin, who have given me permission 

 to freely study the original or authentic specimens kept in the 

 herbaria of these institutions. To these gentlemen the author 

 desires to express his sincerest thanks. 



General Morphology. 



The post-embryonal frond of Alaria is sharply differentiated 

 into three parts, the holdfast, the stipe and the blade or lamina. 

 It is simple for the whole life, neither branches nor stolons being 

 found in the normal forms. It is habitually erect and no dorsi- 

 ventrality is indicated in tlie external appearance and in the 

 internal structure. The stipe is percurrent into the blade running 

 in its median line and elevated equally above both surfaces. The 

 extension of the stipe within the blade is called midrib. 



The tissue elements of the frond are practically equal to those 

 found on other Laminariaceous members. The lacunae or mucilage 

 canals which are common in most species of Laminaria are entnx'ly 

 wanting in Alaria. A peculiar sort of glandular cell, which I^> 

 have called mucilage gland, is present in all Alarias, at least in 

 early stages of their development. 



The so-called cryptostomata are found in some species but 



1) Yendo : On tlie Mucilage Glands of Undaria. 1909. 



