38 



MOSSES AND FERNS 



CHAP. 



oil drops which are so abundant in the undivided germ-tube 

 disappear almost completely, and are doubtless used up by the 

 growing cells. 



According to Leitgeb's view, and that of other authors, 

 the eight-celled body at the end of the germ-tube is a sort of 

 protonema, from which the gametophore arises as a lateral 

 outgrowth. I have seen nothing in the species under consider- 

 ation which supports such a view. Here the axis of growth 

 is continuous with that of the germ -tube, and in some cases 

 at least, and probably always, a single apical cell is developed 



A. 



Fig. 8. — Riccia hirta (Aust.). Germination of the spores, X 190. In E the figure at the left repre- 

 sents a surface view, the one at the right an optical section ; K, germinal tube. 



at the apex at a very early stage. Probably this initial cell 

 is one of the four terminal octant cells resulting from the 

 first divisions. This cell sometimes has but two sets of 

 segments cut off from it at first, alternately right and left, but 

 whether this form is constant in the young plant I cannot 

 now say. 



The four lower quadrants also divide, at first only by 

 transverse walls, and these cells lengthening give rise to a 

 cylindrical body composed of four rows of cells, terminated by 

 the more actively dividing group of cells at the summit. The 

 single apical cell is soon replaced by the group of initials found 

 in the full-grown gametophyte, and the method of growth from 



