Black : The imbedded antheridium in Dryopteris 563 



in which instance the antheridium, also in the apical region, was 

 imbedded under two layers of cells. Approximately half of this 

 antheridium consisted of mature sperms, the other half, that nearer 

 the surface, w^as composed of three cells, two smaller and one very 

 large w^ith a corresponding large nucleus. This last cell bore a 

 striking resemblance to an egg-cell. 



The development of the imbedded antheridium is very similar to 

 that of the antheridium in a lower order of ferns as described by 

 Campbell ('07) in the Ophioglossaceae, with the exception of the 

 first divisions and the development of the cover-cell. An approach 

 to the imbedded antheridium oi Dryopteris stipiilaris and ^'Nephro- 

 dhim inolle'^ is found in the antheridium of Ceratopteris (Engler & 

 Prantl, Nat Pflanzenfam. *02). This antheridium projects but 

 slightly above the surface oS. the prothalHum, although it has the 

 customary lid- and ring-cells. The basal cell, assuming a more 

 irregular shape, is designated as the pedicel-cell. 



II. *' Nefhrodium molle'' 



The origin of the imbedded antheridium in '^Nephrodium molW 

 is similar to that of an archegonium and not unlike that described 

 for Dryopteris stipidaris. After the first division of the initial 

 cell into the outer and inner cells, the inner cell divides periclinally 

 into two unequal ctWs {^figur e 12), recalling the development of an 

 archegonium. If a division of the larger cell should takp place 

 obliquely, a condition would be found as show^n in figure ij. 

 Further divisions of the two inner cells give rise to the condition 

 seen in figure 7^. That such structures would develop into 

 imbedded antheridia seems positive. The structure showai in 

 figure 24, for example, may have originated in a manner similar 

 to that of .an imbedded antheridium, but it is certain that none of 

 these structures would become sporophytes. 



These developing structures found in the apical portion of the 

 prothallia will be seen to be similar to the early stages in the 

 development of the imbedded antheridium of Dryopteris stipularis. 

 Figure i^ in '' Nephr odium molle'' could represent an early stage 

 in the development oi figure 8 in Diyopteris stipuiaris. The cells 

 in these structures differ markedly from the surrounding cells in 

 their granular cytoplasm and large nuclei. Infigu^rs 12-1^, the 



