igi2] CLAPP—ANEURA PINGUIS 183 



canal cells, a ventral canal cell, and the egg cell. The archegonium 

 wall has two layers of cells (figs. 32, 33). The 4-6 canal cells are of 

 short endurance; their walls break down and the cytoplasm and 

 nucleus are transformed into a mucilaginous substance. The egg 

 cell is large and round, its cytoplasm containing many starch 

 grains (fig. 33). When the cap cells bend back, there is a clear 

 passage made in the neck to the egg. Fertilization was not 

 observed. 



As soon as fertilization has occurred, the neck and venter cells 

 divide rapidly, and the whole branch is a thick cushion of cells 

 projecting beyond the margin of the thallus. Usually only one 

 embryo grows on a branch, and where two appear they probably 

 belong to two branches. Two have been reported, however, in one 



6) 



immature 



egg has been fertilized, are carried with the filaments to the 



calypt 



thinks more trichome 



produced on the torus, but this seems unlikely, for many are 

 sloughed off as it develops. Some new rhizoids do grow at the 

 bulbous base. 



Sporophyte 



The first division of the egg is a transverse one into epibasal 

 and hypobasal cells (fig. 34). The hypobasal cell has been said 

 either to form a few divisions or to grow into a lobed haustorial 

 cell (Leitgeb 19). It distinctly becomes a true haustorium (figs. 

 35, 36), rhizoidal in form. Both cells elongate rapidly; the haus- 

 torium sometimes lobes and .sometimes remains straight. The 

 epibasal cell is divided by a horizontal wall into two cells (fig. 35) 

 containing abundant cytoplasm, many plastids, and large nuclei. 

 In this three-celled stage disorganization of the cells of the calyptra 

 around the base of the suspensor is striking. The uppermost cell 

 divides again by a horizontal wall, so that a filament of four cells 

 is formed, including the haustorium. Vertical walls now come in, 

 so that there are three rows of quadrants (fig. 36). 



The lowest tier next the haustorium now forms two rows (figs. 

 37, 38), its vertical and transverse walls having no definite sequence. 

 It corresponds to the foot, and the cells form at first a more compact 



