Some Points in the Structure of Alaria Fistulosa 



Alice L. Kibbe, 

 University of Washington, Seattle. 



K. Yendo (5) reports this sub-arctic kelp as growing luxuriantly 

 from the Kurile Islands to Shikotan Island, on the side towards the open 

 sea. Setchell and Gardner (3) report it from the Kurile Islands to 

 Southeast Alaska. They list none south of Wrangell Narrows. How- 

 ever, Dr. T. C. Frye (1) states that he observed it as far south as 

 Augustine Bay, on Dall Island. 



Setchell and Gardner (3) describe two varieties; A. fistulosa 

 platyphylla as having very broad midrib and lemina, and long narrow 

 sporophylls; A. fistulosa stenophylla as having a narrow midrib and 

 lamina, and short and more or less ovate sporophylls. The material at 

 hand varies so widely in these points that it seems probable that a care- 

 ful investigation would show a gradation from one form to the other. 

 Age seems to cause variation in these characteristics. The older ones 

 show the platyphylla type, while the immature specimens generally show 

 the stenophylla form of growth. Since they so closely resemble one 

 another, all observations will apply to the general species. 



The chief purpose of this paper is to trace the development of 

 the fistulose or chambered character of the midrib (Fig. 21). The 

 chambers form at an early period in the development of the plant. Setchell 

 and Gardner (3) report distinct chambers in blades 15 cm, long. No 

 young material was available. The region of most rapid growth is found 

 in the base of the lamina, and since the chambers arise here, this region 

 furnishes suitable material for investigation. 



The materials used were collected by Dr. T. C. Frye and Dr. G. B. 

 Rigg, on the United States Bureau of Soils Kelp Investigation Expe- 

 dition to Alaska in 1913. The smaller specimens examined were col- 

 lected by Dr. Frye at the Kashevarof Islands, southwest of Wrangell; 

 the larger by Dr. Rigg at Anchor Point, Cook's Inlet. They were pre- 

 served in formalin. This made good sections of the larger chambers 

 difficult to secure, as they warped considerably, even when run from 

 formalin up through 15% alcohol. Only one entire plant was available, 

 but there were numerous pressed and formalin specimens of type regions. 

 Longitudinal sections of the midrib, cut perpendicular to the plane of 

 the lamina, were found best adapted to illustrate the formation of 



(43) 



