94 MOSSES AND FERA^S chap. 



no proper exospore is formed, although the outer layer of the 

 cell wall is more or less cuticularised. 



In the germination of the spores Pellia offers an exception 

 to the other Jungermanniaceae, in that the spores divide into 

 a multicellular body before they are discharged from the capsule. 

 The presence of centrospheres in the dividing nuclei has been 

 recently demonstrated by Farmer.^ The ripe spore here is an 

 oval body which consists of several tiers of cells, the end cells 

 being usually undivided, and the middle ones each consisting of 

 four equal quadrant cells. There is some disagreement as to 

 the earliest stages in the germination and the establishment of 

 the apical growth. Hofmeister - states that in P. epipJiylla one 

 end cell of the spore grows out into the first rhizoid, while the 

 other develops into the growing point of the young plant. 

 Mliller,-^ on the other hand, states that in P. calycina both ends 

 of the spore develop root-hairs while the growing point, which 

 at first has a two-sided apical cell, like that of Metzgeria, arises 

 laterally. 



Connecting the strictly thallose anacrogynous Hepaticae 

 with the foliose acrogynous ones, are a number of most in- 

 structive intermediate forms. Of these Blasia (Fig. 38, F) is 

 perhaps the simplest. Here the margin of the thallus is lobed, 

 and these lobes, according to Leitgeb's ^ view, are very simple 

 leaves. In Fossombronia (Fig. 38, C, D), while the general 

 thallose form is more or less evident, the leaves are unmistak- 

 able, and as their development shows, morphologically the same 

 as the leaves of the acrogynous forms. The most remarkable 

 form, however, is Treubia msignis, a very large foliose Liverwort 

 discovered by Goebel in Java. This has all the appearance 

 of a very large acrogynous form, and also the typical three- 

 sided apical cell ; but in regard to the position of the sexual 

 organs it is typically anacrogynous. These and the Haplo- 

 mitrieae form a perfect transition from the Anacrogynae to the 

 Acrogynae. 



The multicellular gemmae of Blasia^ have been alluded to. 

 These are produced in long flask-shaped receptacles, and when 

 mature form nearly globular brownish bodies whose cells contain 

 much oil, and whose stalk consists of a simple row of cells. 

 Among these are glandular hairs, which secrete mucilage, by the 



1 Farmer (5). - Hofmeister (i), p. 21. ^ Mliller, N. J. C. (i), p. 257. 

 '' Leitgeb (7), vol. i. p. 5. ^ Leitgeb, 'i.e. p. 58. 



