Graham: Conocepiialum conicum 617 



a deeply staining membrane. The inner surface of the venter is 

 stained intensely (^figures /, 6^ jj). The nucleus also is stained 

 deeply, its membrane being easily made out, but the cytoplasm is 

 stained diffusely. 



The nucleus of the fertiHzed eg^ soon divides into two, which 

 usually lie close together {^figures 2, j, 6^ id), but in some cases 

 they may be separated {figure ^). These nuclei are of approx- 

 imately equal size. They may be parallel or transverse to the 

 long axis of the archegonium. A cell wall is not laid down imme- 

 diately after the first division of the nucleus but follows tardily. 



The first division wall is transverse and is, as are all the walls 

 when newly formed, a delicate membrane. In order to be certain 

 that no walls were overlooked, Bismarck brown, which is well 

 known to be one of the best counterstains for cell walls, was used. 

 This division is followed by two or three successive transverse 

 divisions forming either four or five cells {figures 7, 8, p, 11, /j, 



^^^ ^7y 3^)' As in the case of the first division, the formation of 

 a wall is always subsequent to the division of the nuclei. 



In all the material studied, no longitudinal wall was formed 

 until the tier of four or five cells was completed, although about 

 fifty were seen in approximately this stage {figures 7, <?, p, //, ij, 

 ^^f ^7y J^)' Considerable attention was given to this sequence in 

 the formation of cell walls, since the method observed is at vari- 

 ance with that usually described for this family and especially for 

 this species by Cavers ('04). This author describes the young 

 embryo as divided into octants by one transverse and two longi- 

 tudinal walls at right angles to each other. My observations 

 accord more nearly with those of Bolleter ('05), but this author 

 describes and figures only four cells formed by three trans- 

 verse walls. 



The outline of the young embryo differs considerably from 

 that oi Preissta and Marchantia, being elongated parallel to the 

 long axis of the archegonium and broader at the distal than at 

 the proximal end {figures 11^ 12, 16). In the two plants first 

 mentioned it is nearly spherical. 



Figure 12 shows the first longitudinal division at the lower or 

 distal end of the vounfr snoroponlum : 



fig 



figi^ 



