Box.— Vol. II.] HUS—PORPHYRA. 20I 



but a very small amount of jelly surrounding the cells, and 

 it could not swell enough to make an appreciable difference 

 in the thickness of the frond. 



Vegetative cells are but rarely found intermixed with the 

 reproductive cells. 



S^orocarfs. — Each sporocarp contains eight carpospores. 

 They are formed from the vegetative cell by a cruciate 

 division, followed by a division parallel to the surface of the 

 frond. These divisions give rise to two tiers of four carpo- 

 spores each (PL XX, figs, la-nb; PL XXII, fig, 24). 

 Occasionally the vegetative division of the sporocarp 

 mother-cell goes one step farther; so that we find but two 

 carpospores in each sporocarp. 



Antheridia. — The antheridium-mother-cell, by a cruciate 

 division perpendicular to the surface of the frond, gives 

 rise to four antheridia. Each antheridium now underofoes 

 a division parallel to the surface of the frond, then a cruciate 

 division perpendicular to the surface of the frond, followed 

 by another parallel division in all segments. The anther- 

 idium is now divided into sixteen parts, each of which, by a 

 cruciate division, gives rise to four antherozoids; so that 

 the whole antheridium now consists of sixty-four anthero- 

 zoids arranged in four tiers of sixteen each (PL XX, figs. 3a 

 and 33; PL XXII, fig. 27). The direction of the walls laid 

 down by the last cruciate division is often decidedly oblique, 

 so that, when the walls separating the individual antherozoids 

 dissolve, the groups of antherozoids are arranged in the form 

 of a hollow sphere. The wall laid down by the first, paral- 

 lel, reproductive division of the antheridium is thicker than 

 those laid down afterwards, and only dissolves when the 

 frond is fully ripe ; so that for a long time two separate 

 spherical groups of antherozoids exist in each antheridium. 



This spherical arrangement of the antherozoids seems to 

 be peculiar to the plants collected on the Californian shores, 

 since specimens of P. leucosticta collected on the coasts of 

 France and of Helgoland fail to show this. 



Po7'phyra leucosticta was founded by Thuret (1864), and 

 has since been more fully described by Janczewski (1873). 



