Laminaria digitata and Laminaria saccharina. 189 
Briefly summarized, my results are as follows:— 
1. The Laminaria plant is the gametophyte. 
2. The reproductive areas consist of gametangia and paraphyses. 
3. Flagellated gametes escape from the gametangia, and isogamous 
conjugation occurs. 
4. The resulting zygospore divides and gives rise to a chain or mass of 
cells. These may be of the ‘ 2 x ’ type, or the reduction may occur in the 
early divisions of the zygospore. 
5. The cells of this structure rupture, and their contents grow out and 
form the gametophyte. 
6. The young gametophyte consists of a flat lamina, one cell thick, 
and is attached at its base to surrounding objects by a number of unicellular 
rhizoids. 
7 . The cells of the lamina divide, and eventually form the limiting and 
cortical layers and part of the medullary tissue. 
8. The stipe is formed by a modification of the base of the lamina. 
9. Part of the medullary tissue is formed by an upgrowth of cells from 
the base of the rudimentary stipe. 
10. A disk-shaped expansion is formed at the base of the stipe, and 
from this the hapteres originate. 
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