328 Durand : Marchantia polymorpha 



under a bell-jar for five days, when it was fixed in chrome-acetic 

 solution. Figures 70— go were made from this collection. Fig- 

 ures gi—ioi are from plants killed in Flemming's solution June 

 9, 1900. The sections are 8— 10— 12// thick and stained in Dela- 

 field's hematoxylin. 



The unfertilized egg of Marchantia is nearly spherical in form, 

 and is stained intensely by Delafield's hematoxylin. After fertil- 

 ization it elongates slightly, becomes surrounded by a wall, and is 

 stained with difficulty and diffusely with the same reagent (Jigs. 

 70, 71). This difference in staining capacity is marked and con- 

 tinues until the embryo has become many-celled (Jig. pj). Another 

 conspicuous reaction to stain is shown by the inner surface of the 

 wall of the archegonium, which becomes deeply colored, so that in 

 sections the pale embryo stands out in bold relief against the dark- 



en 



The first division-wall in 



the fertilized egg is obliquely transverse. Figures 72-76 show 

 longitudinal sections of five embryos at this stage. These and 

 the subsequent figures have been arranged so that the axes of the 

 archegonia are parallel. In figure 75 the wall is transverse, 

 extremes of obliquity are shown in more advanced embryos 



hile 



transverse sections. 



figures 77 and 84. The second wall is perpendicular to the first, 

 dividing the embryo into quadrants (figs. 77-81). The third (//• 

 82), at right angles to the first and second, divides it into octants. 

 The next divisions are anticlinal (figs. 83-90), and are placed 

 at such a peculiar angle with the second and third walls that 

 essentially similar patterns are presented in both longitudinal and 



_M ura 



80-88 with 8q and go. As a rule anticlinal division has not 

 proceeded far before periclinal walls begin to be laid down (Jf- 

 8 3< 8 5-87)- Further divisions are anticlinal, periclinal, and radial 

 without definite sequence, until a subspherical ball of cells is pro- 

 duced (figs. 01-93), in which the primary division-walls may 

 usually be clearly recognized. Up to this time the embryo has 

 increased but little in size, so that its component cells become suc- 

 cessively smaller as division progresses (cf. figs. 70-93)- 



While the above-mentioned development is proceeding in the 

 embryo, other and more conspicuous changes are taking place in 

 the venter of the archegonium and in the tissue at its base. In 



