42 Vol. XLiri., Art. 1.— K. Yendo : 



3£onstrositi€s of the frond. 



I. Duplication of blade. In one of the specimens of A. 

 tœniata Kjellm. in tlie Herbarium of the Hokkaido Imperial 

 University, Sapporo, one side of the blade is totally doubled, that 

 is to say, two semi-blades are present on one side of the midrib. 

 They are equal in shape and size and are symmetrical with the 

 opposite, single semi-blade. A transverse section near the transi- 

 tion point shows the sheering of the medullary portion into equal 

 parts at its marginal swelling. The semi-blade is duplicated from 

 the ordinary crucial point between the midrib and the blade, with 

 a narrow but roundish sinus in the section. The spanning cortex 

 is found in the normal position but not newly formed for the 

 inner side of the semi- blade (Plate XVI, fig. 4). The tw^o semi- 

 blades run parallel in the usual direction. They have the same 

 thickness as the single semi-blade and all elements of the tissue 

 are represented in due manner and proportion. 



I can not find any evidence explaining the cause of this 

 abnormity. In the transition region there is no symptom of de- 

 formation, there simply being two ridges instead of one to indicate 

 the future development into two semi-blades. The terminal portion 

 of the frond is eroded so that nothing can be induced therefrom. 



Kuckuck^) has observed the duplicate blades in Laminar ia 

 saccharina. Killian^) also notes "Flügelbildung" of a blade in 

 Laminaria digitata. 



IL Ramification of Stipe. In A. p^-œlonga Kjellm. and A- 

 lanceolata Kjellm., we meet very often with a bifurcated stipe. 

 The bifurcation always takes place, as far as our material shows, 



1) Kuckuck : Bemerk, zur Mar. Algenveg. von Helgoland, p. 248, fig. 18. 



2) KiLLiAN : Beitr. zur Kenntn. der Laminarien, p. 472, flg. 26. 



