74 



Ophioi/IossuiH. Tlu'Y arise near the growing point (PI. Vll, Fig. 1 1) 

 and seem to be formed in pretty exact acropetal succession. In 

 tlieir development as well as in their large size they closely 

 resemble Ophioglo.s.suni. The mother-cell divides as in other 

 eusporangiate ferns into an outer cover-cell and an interior 

 one, the mother-cell of the spermatocytes. The form of the 

 mother-cell varies a good deal, being sometimes quite narrow 

 (PI. Vn, Fig. 13) sometimes relatively much broader. In the first 

 instance the first division of the inner cell is usually transverse, 

 while in the broader type it is more commonly longitudinal. 

 This variation was also noticed by the writer in Opluixjlossain 

 pemhtluiii. 



Following the primary division, others are found at right 

 angles to it, and this usually results in eight nearly equal 

 cells placed octant-wise. The subsequent divisions follow without 

 any very definite order so far as could be ascertained, and 

 there finally results a large number of spermatocytes, eacli 

 with a large and dee])ly staining nucleus. The final number of 

 spermatocytes is probably not always the same, l)ut it may 

 be several hundred in the large antheridia, as more than fifty 

 can sometimes l)e seen in a single section (PI. VII, Fig. 16). 



In the cover cell the divisions are all anticlinal, and hori- 

 zontal sections, or surface views, show that like the other 

 Marattiaceae the successive walls are arranged much like the 

 segments of a three sided apical cell, being placed spirally, 

 the last wall cutting out the small nearly triangular opercular 

 cell (PL Vll, Fig. 17 A). Whether the latter is thrown off when the 

 autheridium opens, or is merely broken through is not quite 

 clear, as the opening of the autheridium was not studied in 

 the living state, and this point could not be certainly decided 

 by a study of sections of the empty autheridium. 



The fully developed antheridia project somewhat and they 

 are found close together presenting an appearance when seen 

 in section (PI. Vll, Fig. 11) not wuYike i\va,i oi J^quisetwn or Oj)liio- 

 Ijlossum. As the autheridium develops there are formed the mantle- 



