On the Mucilage Glands of Undaria. 
BY 
IC. YENDO, 
Professor of Botany in the Tohoku Imperial University , Sapporo, Japan. 
With Plate XL VIII. 
I N describing Undariopsis ( Laminaria :) Peter seniana, Miy. et Okam., 
Dr. Okamura 1 has noted a peculiar structure in the subepidermal 
layers of the lamina. As the original paper seems to have but a narrow 
circulation, it will be desirable to quote here the lines which relate to the 
subject : — 
‘ Over both the surfaces ot the lamina, both younger and older, minute 
dark dots are thickly scattered, which are easily visible to the naked eye. 
In a cross section of the lamina we find beneath the cortical layer a 
roundish-triangular or depressed-conical, deep reddish brown mass enclosed 
in a hyaline bag, situated beneath a minute hole left in the epidermal layer. 
On the surface-view of the lamina, epidermal cells appear to converge 
towards the hole. The chemical nature of these masses I did not study. 
It may perhaps be an excretion. I mention this here especially, for the 
presence of dots in this species is so characteristic that it is sufficient in 
itself to distinguish the species from all others.’ 
A similar body has been found by Prof. Miyabe in Utidaria pinncitifida, 
Sur., and its variety distans, Miy. et Okam., and by the present writer in 
Hirome undarioides , Yendo. I have compared the ‘ dots ’ of these species 
and made it clear that they have similar characters in various respects, 
however much the species may differ. It is very probable that the 
problematic bodies found in the three genera may be identical in their 
properties, functions, and mode of formation. But the material studied 
was all from dried specimens, and, as regards the nature and function 
of the £ dots’, nothing could have been added to the discoverer’s remarks. 
A stay of two weeks at the Oshoro Marine Station in December last 
1 Okamura: Enumeration of Algae of Japan (in Japanese), p. 128. 1902. (Diagnosis of the 
genus not yet published). Ibid.: On Laminariaceae of Japan. Bot. Mag. Tokyo, vol. x, p. 99. 
1896. Yendo: Three New Algae from Japan. Ibid. : vol. xvii, p. 102. 1903. 
[Annals of Botany, Vol. XXIII. No. XCII. October, 1909.] 
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