Notes on the Sori of Macrocystis and Postelsia. 85 



is of long thick -walled cells. Large mucilaginous canals embedded 

 in the outer cortex occur all over the leaves. 



The reproductive bodies are borne on the fertile leaves, which are 

 produced from the base of the plant on special branches. They are 

 much like the vegetative leaves in appearance, being long and narrow, 

 and bordered with spines ; but they are destitute of air-bladders, and 

 are more regularly and deeply furrowed than the floating leaves. 



In the various descriptions hitherto published of the fruit of Macrocystis, 

 the sporangia have been described as occurring in irregular son', or in 

 patches on the lamina of the fertile leaf ; but this does not seem to 

 be an exact or adequate description. In the plant examined, M. 

 pyrifera, Ag., they are confined to the depressions on either side of the 

 furrowed leaf (plate XX., fig. i) ; they are not, however, invariably present, 

 and the furrows may be empty for considerable spaces. The tissue 

 of the fertile leaf resembles that of the vegetative leaf; the sporangia 

 which arise by repeated division of the epidermal cells are stout, club- 

 shaped bodies (plate XX., fig. 3), and are surrounded and over-topped 

 by the dark-brown paraphyses. These also arise from the epidermal 

 cells ; they are club-shaped, but more slender than the sporangia (plate 

 XX., fig. 3), and are full of dark-coloured contents. 



The sporangia, as already stated, occur in the hollow part of the 

 furrow in longitudinal sori. The furrows are comparatively wide at 

 the base, and so closely pressed together that those adjacent almost 

 touch each other (plate XX., fig. i) ; the outlet is further closed by a 

 projection of the tissue of the leaf, which, from each side, bends over 

 the sorus (plate xx., fig. 2). The cells of the epidermis and outer 

 cortex forming the projection are elongated parallel to the surface of 

 the leaf, and, by narrowing the entrance of the furrow, afford additional 

 shelter and protection to the growing and ripening fruits. A section 

 across the fertile leaf has thus the appearance of a row of conceptacles, 

 and forcibly recalls in appearance the conceptacles of Splachnidium and 

 other brown Algae. 



Postelsia palmceformis is, so far as is at present known, limited in 



its habitat to the coast of California. It is of interest to note that the 



Pacific Coast of North America, otherwise rich in Laininariacece, is 



especially characterised by the number of peculiar genera which it 



possesses, i.e., Dictyoneuron, Postelsia, Nereocystis, Cymathere, Pterygophora, 



Egregia, and Eisenia, many of them monotypic and limited to California. 



The only description of Postelsia palmceformis is that given by 



Ruprecht (Nene oder nnvollstandig bekannte Pflanzen aus der nordlicJien 



Theile des Stillen Oceans) from material collected on the shores of 



