170 MOEPIIOLOGY. 



lowest they are entirely wanting ; in the Marchantiacece they appear as 

 small membranous narrow strips upon the lower side of the flat stem. In 

 the Jungermannice the most frequent form is the bifid, folded together, 

 and often associated with stunted leaves at the lower side of the recum- 

 bent stem. We still require more comprehensive observations of the 

 history of the development of leaves than Gottsche (loc. cit.} has been as 

 yet able to afford us. In the bifid leaves we must mention the peculiarity 

 that in the smaller lobes, which are at first always flat, the cells some- 

 times increase only on the surface, and not at the margin, expanding in 

 such a manner that the surface is inflated like a bladder, until finally the 

 lobe of the leaf becomes hood-shaped. 



I must refer to what is stated under the head of the Lichens and 

 Mosses for the import of the particular cells of the parenchyma of the 

 leaf and stem, which, regarded as peculiar organs (the so-called gemmce, 

 brutknospen), dev elope into independent plants. According to Bischoff 

 (Bot. Terrain.), both the cells of the stem (Jungermannia bidentata) and 

 those of the leaves (J. exsecta) separate themselves as propagative cells 

 (Brutzellen) from the plant, and isolated cells shoot out and develope 

 while still connected with the parent plant into small cellular bodies ( J. 

 violacea), which separate from the plant, and grow into new plants, as in 

 Mnium androgynum among the Mosses. The development of these 

 structures had been thoroughly worked out by Mirbel in the case of 

 Marchantia potymorpha. 



98. The organs of reproduction in Liverworts do not differ 

 essentially from those of the Mosses ; but the envelopes appear 

 more clearly as special organs, or as more decidedly distinct from 

 the other foliar organs. 



A. A definite number of leaves, differing more and more in form 

 from the others, as we examine them^from without inward (or upon 

 the stem from below upwards), partly unconnected and partly 

 growing together at their lower part, surround the organs serving for 

 the formation of the spores, and thus compose a blossom (Jlos). Here 

 we may frequently distinguish an inner circle of essentially dif- 

 ferent leaves generally grown together into a cup-like form, as 

 constituting the perianth (perianthium). Between these and the 

 origin of the fruit a peculiar cup-like organ (calyx, Gottsche) is 

 often found, which is sometimes developed downwards in a re- 

 markably unequal manner on the opposite sides, so that the pe- 

 duncle of the fruit arises from the base of a hanging sac. In most 

 Liverworts these blossoms are single ; in many they are, however, 

 grouped together in a definite manner upon a flat stem, and thus 

 form an inflorescence (i'nflorescentia). In this we may distinguish 

 the blossoms from the stalk supporting them, the peduncle (rhachis), 

 on which the blossom always forms a small head. The end of the 

 peduncle is sometimes simple, as in Lunularia ; sometimes expanded 

 in a knob-like form, Grimaldia ; and sometimes either shield- or disc- 

 shaped, when it is generally lobed, as in Marchantia. 



We cannot speak specially of the formation of the blossom in the 

 Liverworts, and of the calyx in its two forms (if indeed the two structures 

 really have the same signification), until we have obtained those fuller 



