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



division of the antheridium-mother-cell each sporocarp cor- 

 responds to four antheridia. 



The author distinguishes between a vegetative division 

 and a reproductive division by the aid of the partition walls 

 laid down by these divisions. A jelly-wall formed after a 

 vegetative division is, as a rule, much thicker than one 

 formed after a reproductive division. Furthermore, a wall 

 of the latter kind dissolves when the frond is fully ripe, so 

 that the reproductive bodies become arranged more or less 

 irregularly; something which is very clearly shown in the 

 antheridia of P. leucosticta. 



The first reproductive division of the antheridium is 

 parallel to the surface of the frond, corresponding to the 

 first transverse division of the sporocarp, and is followed by 

 a cruciate division in both segments. In fact, parallel and 

 cruciate divisions alternate until the number of antherozoids 

 peculiar to the species has been formed. The only differ- 

 ence, therefore, between antheridia and sporocarps lies, if 

 we do not consider their origin, in the larger number of 

 divisions which the former undergo. 



Though the manner of division of antheridia and sporo- 

 carps is fairly constant, yet a large number of variations 

 take place. The most frequent among these is the direc- 

 tion of the last division in either antheridia or sporocarps, 

 which is not necessarily parallel or perpendicular to the 

 surface of the frond, but is often oblique, and is occasion- 

 ally omitted altogether in some of the segments of the spo- 

 rocarp or antheridium. Rarely an additional division takes 

 place in some or all of the segments of the sporocarp or 

 antheridium. 



Cases have been met with, where the vegetative division 

 of the antheridium-mother-cell is not as evident as usual, 

 and the whole vegetative cell apparently becomes an 

 antheridium, so that four times the usual number of anther- 

 ozoids are formed. 



Occasionally the first cruciate division of the sporocarp- 

 mother-cell is vegetative instead of reproductive, and only 

 one-fourth the usual number of carpospores are found. 



