182 PROCEEDINGS OF THE AMERICAN ACADEMY 



appears to be prolonged into the blade one third to one half the way 

 up, as a sort of broad midrib. The midrib-like portion is rather 

 wide at the base, and tapers gradually to a point. The edges are 

 not straight lines, but are somewhat notched or toothed. As seen 

 with the lens, the apex of this portion is not acute, but is somewhat 

 blunt. (Cf. Figs. 1 and 2.) 



The midrib is very striking in fresh specimens as it is of a deeper 

 color than the rest of the blade. When examined with a low power 

 (150 diameters), it is seen to be thicker and of more complex structure 

 than the rest of the blade, which appears on focusing to be a simple 

 membrane composed of a single layer of cells. The further details 

 of this structure properly come under the sections devoted to the 

 histology. 



On some of these young specimens are to be found small clusters of 

 hairs arising from the surface not only of the more complex portion, 

 but also in some cases from the membranaceous outer part of the blade. 

 These are the cryptostomata or " Fasergriibchen." By the presence of 

 these organs the young plants of Saccorhiza dermatodea may be dis- 

 tinguished from the young plants of any of the other species of Lam- 

 inariecB of the New England coast, except from those of species of 

 Alaria. From these they may be distinguishetl, after a little experi- 

 ence, by the outline and the color. Saccorhiza dermatodea in these 

 early stages is usually elliptical to obovate, while the species of Alaria 

 uniformly have a narrowly linear frond. The color of the young 

 Saccorhiza is light brown. They become somewhat greenish in dry- 

 ing at times, but generally take on a more yellow tint. The young 

 AlaricE are of a much lighter brown, and become decidedly greenish 

 on drying. The midrib-like portion in Alaria, too, is more linear in 

 shape, and narrower, more like a real midrib. As soon as the Alaria 

 attain any considerable size the true midrib makes its appearance, and 

 distinguishes them at once from the young plants of any of the other 

 species. 



2. Later Stages. — As the specimens become larger a number of 

 changes may be noticed, which are well shown in a specimen about 

 o cm. high. This specimen possesses a distinct organ for attachment, 

 consisting of the slightly dilated basal portion of the stipe and a 

 sort of small cushion by which this is attached to the substratum. 

 The cushion has a spongy appearance and a dirty brown color, and 

 differs decidedly from the stipe both in color and consistency. The 

 stipe itself is about 3 mm. high and about 0.5 mm. in diameter. It is 

 cylindrical in shape, and expands gradually into the lanceolate or 



