II 



MUSCINEA^— HEPATIC JE—MARCHANTI ALES 



37 



takes place the chloroplasts are abundant and conspicuous. 

 The formation of the first rhizoid does not take place usually 

 until a number of divisions have been formed in the young 

 thallus. The first rhizoid (Fig. 9, r) arises at the base of the 

 germinal tube, and is almost free from granular contents. It, 

 usually at least, is separated by a septum from the germ-tube. 

 The first wall in the latter is usually transverse, although in 

 exceptional cases it is oblique (Fig 8, C), and this is followed 

 by a second one parallel to the first (Fig. 8, C). In each of 

 these cells a vertical wall is formed, and then a second at right 

 angles to this, so that the nearly globular mass of cells at the 



Fig. 8. — Riccia trichocarpa. Germination of the spores, X 190. In E the figure at 

 the left represents a surface view, the one at the right an optical section; K, 

 germinal tube. 



end of the germ-tube is composed of eight nearly equal cells or 

 octants. As these divisions proceed the oil drops which are so 

 abundant in the undivided germ-tube disappear almost com- 

 pletely, 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 pro- 

 tonema, from which the gametophore arises as a lateral out- 

 growth. I have seen nothing in the species under consideration 

 which supports such a view. Here the axis of growth is con- 

 tinuous with that of the germ-tube, and in some cases at least, 



