324 Durand : Marchantia polymorpha 



tudinal or transverse or both, as may be seen by inspection of 

 figures 9-24. In the distal or antheridial cell, however, the divi- 

 sions are regular. It soon segments transversely into either two 

 {figs. 7-12), or three {figs, ij-20), or perhaps rarely four cells 

 {cf. figs. 21, 2j). I have not seen more than two transverse walls 

 in any antheridium at this age, a greater number of walls, so far 

 as my observation goes, always appearing in organs which have 

 progressed considerably in their development, so that they were 

 probably formed subsequently to vertical division {cf. figs. 24, 2j). 

 Each cell of the antheridium now soon divides by a vertical wall 

 into two. This division usually appears first in the proximal cells 

 {figs. 10, 14-18)1 but occasionally the distal one divides first {figs. 

 n y 12). These vertical walls are then followed by others at right 

 angles to them in each cell so that the young organ consists of 

 two or three tiers of four cells each. In each cell of each tier now 

 appears a periclinal wall separating it into an inner spermatogenous 

 cell and a peripheral wall-cell. This periclinal division begins at 

 the base of the antheridium and progresses toward the apex {figs. 

 19-2J), so that the interior spermatogenous cells are finally com- 

 pletely enclosed by the enveloping wall. Further divisions in the 

 latter are entirely radial, so that it remains a single layer of cells 

 in thickness. 



The young antheridium now increases rapidly in size. The 

 stalk divides transversely and vertically so that it ultimately con- 



sists of 5 



{figs 



(A 



(fig 



The original 



division-walls remain evident even in the mature structure. 

 Figure 29 represents an antheridium about one fourth to one third 

 grown. The mature organ is similar in form but is much larger 

 and contains a much greater number of cuboidal cells, formed by 

 repeated division of the inner cells. A group of such cells from a 

 fully grown antheridium is shown in figure 30. The next division 

 in each cuboidal cell is diagonal, so that two triangular ceils or 

 spermatids result {fig. 3 i). According to Ikeno ('03) and Camp- 

 bell ('05), this final diagonal division is unaccompanied by a wall 

 in Marchantia and Fimbriaria. My own preparations stained wP 

 Delafield's hematoxylin, which brings out cell-walls clearly, shows 



