THE HIGHER CRYPTOGAMIA. 43 



the shoot then consists simply of a double row of cells 

 (PL V, fig. 25). 



A third mode of origin of lateral axes takes place at the 

 approach of fructification. On the under side of the mid- 

 rib, attached not exactly in the middle, but laterally either 

 to the right or left, there is formed, at some little distance 

 underneath the end of the stem, a cucullate leaf, in the 

 axil of which a branch is developed, but only to such an 

 extent as to form a flat cushion-shaped process. On its 

 upper surface are produced either archegonia or antheridia. 

 The antheridia, in structure and development, are exactly 

 like those of most of the leafy Jungermanniae, e. g. Radula 

 complanata. The archegonia, which are short and thick, and 

 only six cells in height, are situated, like the antheridia, 

 usually from four to seven in number, in the axil of a leaf. 

 Their regular mode of cell-development resembles that of 

 Pellia ; in Metzgeria, also, the large size of the cells of 

 the archegonium facilitates observation (PL V, fig. 30). I 

 have not had an opportunity of investigating the develop- 

 ment of the fruit of Metzgeria. In spite of the countless 

 multitudes of apparently healthy archegonia and antheridia 

 produced by the thick patches of Metzgeria fur cat a, 

 which in our hilly districts clothe the masses of rock 

 in shady, moderately damp localities, the fruit is very 

 rarely met with. Probably, the cause of this remarkable 

 fact is to be found in the drought which prevails in the 

 habitats of the plants at the period of the ripening of the 

 antheridia, viz., the middle of June. 



The species of Aneura {A. pinguis and vndtifda), not- 

 withstanding the great difference of their habit from that 

 of Metzgeria, exhibit the same kind of development at the 

 ends of the stem (PL VI, figs. 2, 11). There is, however, one 

 essential difference, viz., that the cells of the second order, 

 even before their division by the septa perpendicular to the 

 surface of the stem, divide by septa paratlel to that surface. 

 This division is repeated rapidly and frequently, after 

 the manner of the growth (in thickness) of Pellia (PL VI, 

 figs. 3, 12), so that the shoot increases very rapidly in 

 thickness ; longitudinal sections through its growing end 

 have a parabolic form. 



