64 H0FME1STER, ON 



sues a most active and long-continuing multiplication of 

 the cells of the base of the leaf, which gives the leaf its 

 final shape. 



The leaf- development of the different Jungermannias, which 

 I have endeavoured to describe in the preceding pages, may 

 be looked at from one and the same point of view. How- 

 ever different at first sight -the individual processes may 

 appear, they may be looked upon collectively as a tendency 

 in the longitudinal halves of the young leaf-rudiments to 

 develope themselves independently, and often unequally. 

 The upper and lower lobe of the leaves of Scapania, Frulla- 

 nia, Radula, &c, answer to the two tips of the leaves of 

 Lophocolese, Jung, bicuspidata, Ptilidium, and others. 



The mode of ramification of the Jungerrnannise is very 

 difficult to unravel, on account of the nature of the terminal 

 buds. I have not arrived at an entirely clear idea of it in 

 any species. Many observations point to the conclusion 

 that the normal ramification of the axis results from a 

 genuine furcate division of the naked apex of the terminal 

 bud above the place of origin of the youngest leaf {e.g., PI. 

 VII, fig. 1, Ptilidium ciliare), and there is nothing opposed 

 to this view. The cases which appear to contradict it (such 

 as the development of new shoots out of the axils of the 

 leaves of fruit-bearing, or even older branches of terrestrial 

 Jungermanniae), may be looked upon as the development 

 of adventitious buds. 



These shoots in /. bicuspidata often attain the length of 

 several millimetres without producing leaves. They are, 

 therefore, just the objects in which the nature and method 

 of cell-multiplication in the apex of the stem of Jungermannise 

 may be most conveniently investigated (PI. VIII, fig. 12 fl ' h ). 

 The half- subterraneous shoots of Haplomitrium Hooker i often 

 remain in like manner leafless for a considerable extent. 

 These are the processes which Gottsche is inclined to con- 

 sider as being true roots of this liverwort, which is entirely 

 unprovided with rootlets ('Nova Acta Acad. C. Leop.,' vol. 

 xx, 1, 275). I had the opportunity of convincing myself 

 that the structure of the growing end of these shoots en- 

 tirely coincides with that of the end of the stem (PI. VII, 



