178 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



The base in Por^hyra varies from cuneate to cordate, or 

 even umbilicate, and is sometimes cucullate, as in P. nereo- 

 cystis. These various forms of base depend just as much 

 as size, etc., upon age, zone, and locality. An umbilicate 

 base is found on the fronds of plants growing on flat sur- 

 faces (P. laciniata f. timhilicalis)\ one is liable to meet 

 with a cordate base in the older fronds ; while a cuneate 

 base is found on the fronds of plants which grow in exposed 

 places. 



In the genus Por-phyra, we may distinguish between two 

 kinds of attachment, the one cushion-shaped and paren- 

 chymatous, the other discoid and rhizoidal. The latter 

 form of base has been ampl}^ discussed and illustrated by 

 Bornet and Thuret (1878), and it will suffice to say here 

 that the cells in the immediate neighborhood of the base 

 produce rhizoid-like projections, in thickness from two- 

 tenths to one-tenth the diameter of the cell, which grow 

 down through the jelly between the cells and the cuticle. 

 That these h5^ph£e actually grow, and that the older the 

 plant grows the more of these projections are produced, is 

 demonstrated by treating the base of a young specimen of 

 Porfhyra perforata with Schultze's macerating fluid. This 

 dissolves the jelly, and the weight of a cover-glass crushes 

 the preparation sufficiently to show the details. From each 

 of the thick-walled cells near the base, a hypha may be 

 seen growing out, which may be longer or shorter, some 

 being even but a few microns in length. Their course is 

 more or less direct. Most of them extend down to the 

 -substratum. Consequently, though the frond about one 

 centimeter above the base is normal, the part lower down is 

 very much thickened by an ever increasing number of these 

 projections, which finall}^ form a dense network, in which 

 it is impossible to trace the individual hyphse. According 

 to Agardh (1882), these hyphse possess no septa, at least, 

 he has been unable to see them; for he observes: " Hsec 

 fila radicantia Porphyrse mihi semper inarticulata obvener- 

 unt, * * * ," They are long, slender, tapering threads, 

 averaging one to two microns in thickness. Of course, the 

 longer they become, the less evident their tapering nature 



