l8o CALIFORNIA ACADEMY OF SCIENCES. (Proc. 3D Ser. 



At first it seemed exceedingly improbable to the author 

 that the cells to which the function of the attachment of the 

 frond was delegated should finally produce fruit; but a 

 knowledge of the fact that the formation of spores in these 

 cells was observed by Bornet and Thuret (1878) led him 

 to make a more careful study of the basal cells. Up to 

 this time, however, the author has been unable to demon- 

 strate a single cell which both emitted a hyphal thread and 

 bore fruit, though the oldest obtainable specimens were 

 investigated. It must therefore be concluded that if ever 

 the contents of these cells are transformed into spores, this 

 must be but rarely the case. 



The areolate, lighter colored portion of the frond, about 

 one centimeter in diameter, directly surrounding the attach- 

 ment found in all specimens of Porfhyj'a as known to the 

 writer, with the exception of P. naiadtim, probably finds its 

 reason in two causes. The first is the partial loss of color 

 of the cells near the base, caused by decreased activity 

 owing to the large number of rhizoid-like projections which 

 separate them from the surface of the frond. The other 

 cause may be looked for in the large number of rhizoid-like 

 projections with hyaline walls, resulting in an increased 

 thickness and consequently increased density of the lowest 

 part of the frond. 



Some of the species of Porphyra are slightly stipitate. 

 On this coast only P. leucosticta shows this to any marked 

 extent. The stipes appear to possess the same structure as 

 the discs. 



A cushion-shaped base is, as far as the writer is aware, 

 found in but a single species of Porphyra, viz., P. naiadtim 

 And., a species peculiar to the Pacific Coast. P. naiadum 

 has been found growing on eel-grass, either on Phyllo- 

 spadix in exposed places in the sublitoral zone or on Zos- 

 tera, sheltered, in lagoons. 



On examining the blades of Phyllospadix during the win- 

 ter months, we find here and there small reddish brown, 

 cushion-shaped growths, which to the superficial gaze 

 appear like colonies of diatoms. Continued observation 

 shows a gradual increase in the number of these wart-like. 



