BoT.— Vol. II.] 



HUS—PORI'HYKA. 217 



corresponding cell on the other side of the frond becomes 

 a sporocarp. Sometimes vegetative cells are found among 

 the reproductive cells to a greater or less extent. Some- 

 times specimens are met with which are dioecious or nearly 

 so ; but the majority of the fronds are monoecious. 



6>oroc«r/s.— The number of spores in each sporocarp is 

 four or eight. The sporocarp divides into four parts by a 

 cruciate division. The division may take place in one 

 direction only (perpendicular to the surface of the frond), 

 or one line only may be perpendicular and the other paral- 

 lel to the surface. These divisions would give rise to four 

 spores in one tier or to four spores in two tiers of two 

 spores each. A cruciate division perpendicular to the sur- 

 face seems to occur most frequently. In this case a third 

 division, parallel to the surface of the frond, sometimes 

 takes place, thus giving rise to eight spores in two tiers of 

 four each (PL XX, figs. 13^ and 13^; PL XXII, fig. 24). 

 In making these observations care was always taken to 

 select an absolutely ripe portion of the frond. 



Anther idia.—^\^^ division of the antheridium-mother-cell 

 goes one step further than that of the sporocarp-mother- 

 cell, a cruciate vegetative division perpendicular to the sur- 

 face of the frond taking place before the formation of the 

 antheridium proper is begun. A sporocarp therefore corre- 

 sponds to four antheridia. Each of these antheridia sur- 

 rounds itself with a wall of jelly. By subsequent divisions, 

 the first parallel to the surface of the frond, the second a 

 perpendicular cruciate division, and the third again parallel, 

 there arise sixteen antherozoids arranged in four tiers of 

 four each (PL XX, figs. 13^ and 13*^; PL XXII, fig. 26). 

 This number may, however, vary, and from two causes. 

 The division of the antheridium-mother-cell is sometimes 

 incomplete, so that each antheridium becomes four times as 

 large as the normal ones. Usually in such cases an addi- 

 tional reproductive division takes place, so that each anther- 

 idium possesses sixty-four antherozoids. Frequently also 

 the divisions in the antheridium are incomplete, so that the 

 number of antherozoids is less than sixteen. 



