564 Black: The imbedded antheridium in Dryopteris 



nuclei of the cover-cells have recently divided, whereas the nuclei 

 of the inner cells are in a resting stage. A typical imbedded 

 antheridium similar to those found in Dryopteris stipularis is seen 



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\Xi figure 75. It projects slightly above the surface now but prob- 

 ably did not in its earlier stages. Three cells of the cover are 

 shown in the section. The developing sperms are quite normal, 

 the cells having rounded up, with the blepharoplast showing 

 plainly in some of them. As was the case in Dryopteris stipularis^ 

 both kinds of antheridia appear on the same prothalHum, In some 

 cases an imbedded antheridium will be seen very near a superficial 

 one. In figure 16, a small imbedded antheridium is seen adjoin- 

 ing one of the superficial type. There is a slight variation In the 



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basal cell of this last antheridium, inasmuch as it has redivided 

 until it consists of at least three cells. In the imbedded antheridium 

 are a few almost mature sperms, lying loosely in the antheridia! 

 cavity. Two very narrow cells are at the base of this anthe- 

 ridium. It is very often the case that some of the cells immedi- 

 ately surrounding the antheridium are narrow. An antheridium, 

 which had a deep-seated origin but in its development projected 



considerably above the surface of the prothallium, is pictured in 

 figure 77. 



Figures 18 to 2^ comprise a series of drawings from consecu- 

 tive sections of one prothallium. There are three structures here 

 whose origin is similar to three adjacent archegonia. In figure 18 

 two cells with the superficial or cover-cell are seen. The wall 

 separating these two cells is diagonal, recalhng a similar condition 

 in Dryopteris stipularis {figure 2), This in itself is an irregularity 

 for the normal division of an archegonium initial. The next sec- 

 tion {figure ig^ a^ shows the same two cells ; the innermost cell is 

 a little the larger as is seen in the successive sections. This first 

 structure contains, in all, four cells {figures 21-23). The other 

 two cells are also divided by a diagonal wall, the position of this 

 wall being at right angles to the wall separating the first two cells. 

 The wall dividing the two pairs of cells is in the plane of the page. 

 The beginning of the second structure Is seen \n figure ig, b. It 

 appears here as a little hump of three cells, part of the cover. 

 The next section {figure 20, b) shows that beneath this cover are 

 two cells, one projecting up Into the little hump. In figure 21, b, 



