EOT.— Vol. II.] HUS—PORPHYRA. 179 



is. In fact, the diameter of the larger hyphae appears to be 

 the same for the whole length. While the majority agree 

 in this regard, if we follow them down to the base a differ- 

 ence soon becomes apparent. Some of the hyphas come to 

 an abrupt end, their diameter remaining constant, the con- 

 tents remaining hyaline and parietal, and no septa being 

 present; but others show a greater or lesser increase of 

 thickness at the tip for a greater or lesser length, and a few 

 even branch or at least show indications of branching 

 (PL XX, figs. 7-10). In some of these, septa have been dem- 

 onstrated. The swollen ends contain protoplasm. Whether 

 these ends are to be considered as haustoria, and whether 

 the hyphas enter the cells or intercellular spaces of the host- 

 plant, or whether they merely adhere to the substratum, 

 are questions to which the author can give no definite reply. 

 In sections of the base of a specimen of Porphy^-a perforata 

 which grew on Phyllospadtx, it was impossible to deter- 

 mine the course of the hyphas. The same was true for 

 plants growing on wood. Young specimens of Por-phyra 

 ■perforata growing on barnacles were treated with one per 

 cent, nitric acid; but after dissolving the calcium salts, it 

 was impossible, partly owing to the confusing mass of par- 

 asitic alg£e which flourished in large numbers on and in the 

 shells, but especially to the presence of chitin, to follow 

 the hyphae in their course. 



The ever increasing number of hyphag adds considerably 

 to the thickness of the frond, the latter within one-half a 

 centimeter of the disc often measuring two hundred microns 

 or more, while the strength must be increased a hundred- 

 fold. The cells which give rise to these hyphce, especially 

 those situated more towards the disc, are but imperfectly 

 seen, even in a specimen not quite four centimeters long, 

 being obscured by the hypha-like projections which sur- 

 round them. It is easy to conceive that being thus partly 

 excluded from the light these cells should undergo some 

 change. They lose their purplish color, have yellow- 

 brown cell-contents, and their walls are considerably 

 thickened. 



