Black: The imbedded anthertdium in Dryopteris 5G5 



these cells are seen plainly with their large nuclei. The similarity 

 between this and the two-celled stage of an archegonium is strik- 

 ing. Below these two cells in the second structure [b) are three 

 more cells {figures 2i-2j, b). In these three cells, of which all 

 three nuclei are stcn, one cell is superimposed on the one below, 

 the two nuclei appearing one above the other. The wall of the 

 third cell is indicated by the dotted lines. The second structure 

 (b) consists therefore of five cells, lying beneath a cover which 

 arches slightly upward. 



The third structure (c) is first seen in figure 21, c. Three 

 small cells here project slightly at the left of the second structure 

 [b). The next section [figure 22 , c) shows this projection, cone- 



r 



sponding to the neck of an archegonium, to be much larger. In 



i 



this figure are seen three cells belonging to the third structure. 

 The cells of the three formations are seen here [figure 22) to lie 

 together as one mass of actively growing cells. From their position 

 in the apical region of the prothallium and from their dissimilarity 



1 



to the surrounding cells, i. e.^ their granular, densely staining 

 cytoplasm, large nuclei and absence of chloroplasts, these struc- 

 tures undoubtedly came from potential sex-cells. Figure 2j^ e, 

 shows a section cut through the so-called neck of the third struc- 

 ture. Two small cells are seen in the neck-like projection, beneath 

 which are three cells [figures 2j^ -?/, r). Below these three cells 

 are two more, making a total of nine in this structure [figure 

 2^^ c). The character of these last two cells justifies the opinion 

 that this structure is of archegonial origin. The two cells men- 

 tioned seem to correspond to an egg- and ventral canal-cell of an 



archegonium. 



The cultures of ^^ Nephrodiiun molW presented the same 



general characteristics as those of Dryopteris stipularis grown 

 under these conditions, differing only in the rapidity of growth, 

 these prothallia not growing quite so slowly as those o^ Dryopteris 

 stipularis. No apogamous sporophytes w^ere found on these pro- 



thallia. 



General Considerations 



From the foregoing description of the structures obtained 

 through vaiying the normal cultural conditions, it will be seen 

 that the prothallia of Dryopteris stipularis and " NepJirodium molle " 



