50 



der kelp grows near shore attached to the sea bottom and 

 reaches to the surface of the water, upon which the larger part of it 

 floats. The plant may be divided into three main regions : a hold- 

 fast, a stem, and a crown. The holdfast is made up of root-like 

 processes which attach themselves to the rock, or to a fragment 

 of rock, and they form a body that may reach a diameter of two 

 feet or so. The holdfast is so securely attached to its founda- 

 tion that, if it is a boulder, the rock in a storm may be dragged 

 by the kelp from its bed to a place high on the beach. 



The stem of this kelp is for the most part hollow and of va- 

 riable diameter. Where the stem leaves the holdfast, it is less 

 than an inch in diameter, and it gradually increases the diameter 

 until, at a place just below the free end, it may be three or more 

 inches in transverse section. The stem ends in an enlargement, 

 beneath which it is somewhat constricted, and to the oblong en- 

 largement the name of bladder or cyst is given. The bladder is 

 hollow and its cavity is continuous with that of the stem. The 

 cyst may attain a length of eight inches, although commonly it is 

 considerably less. The wall of the stem, where it is hollow, 

 and of the cyst is about half an inch in thickness. 



The crown is composed of two groups of leaves or sporophylls 

 attached to the free end of the bladder. They are entire and 

 leathery, and like the rest of the plant, are smooth. The leaves 

 vary much in length but seldom exceed three feet, and in the plants 

 examined they are on the average one inch wide, tapering somewhat 

 toward the end. They bear, in certain areas called sori, masses of 

 asexual reproductive bodies. It need hardly be said that all of the 

 measurements vary with the age of the plant. Those which I have 

 given may probably be regarded as the maximum in the species 

 as I have seen it. Much larger figures are given by observers 

 farther to the northward. 



The relation of the bladder kelp to the impact of the waves is 

 such that it is subjected to stresses almost exclusively of one 

 kind, namely, to pulls in a direction parallel to the long axis. 

 The pounding to which some kelps, as for instance the sea palm, are 

 subjected by the waves seems to be entirely wanting in the pres- 

 ent case. The endeavor of the plant to keep to the surface of 



