438 INTRODUCTION TO CRYPTOGAMIC BO'l'ANY. 



The protoplasm first generates a number of starch granules, 

 and after a time these are absorbed, and a double spiral, con- 

 sisting, however, of a single thread, is formed on the walls, 

 Mr. Henfrey compares this very correctly to a piece of string 

 doubled and then twisted* This is not, however, the only 

 part of Marchantia in which spirals are developed in the cells ; 

 for in the walls of the sporangia, the cells are partly annular 

 and partly distinctly spiral. 



481. Thuret has illustrated the spermatozoids of Mar- 

 chantia, Fegatella, and Targionia, in his memoir on the 

 fecundation of Algee so often quoted. They resemble those of 

 Chara, but in an early stage have fewer volutions in the 

 spiral, which at a later period is almost completely expanded 

 (Fig. 91,/). Marchantiacece are divided into three distinct 

 groups, according to the character of the fructification. 



TargioniecE. — Sporangium soli- 

 tary, sessile. 



JecoraricE. — Sporangia on a com- 

 mon pedunculate re- 

 ceptacle. 



LunulariecE. — Sporangia on a com- 

 mon peduncle. 



1. Targionie^, Nees. 



Targioniace^, Endl. 



Frond horizontal, foliaceous. Fruit terminal, inferior, sessUe, 

 with a bivalved single fniited involucre. Sporangia nearly 

 sessile, bursting irregularly or with six teeth. 



482. This tribe consists of two genera, one of which is dis- 

 tributed over almost the whole world, extending as far south as 

 New Zealand and the Swan River ; the other, as far as at pre- 

 sent known, is confined to Cuba. Targionia grows on sunny 

 banks, and in some countries, as in Portugal, is almost always 

 accompanied by Lunularia, though they have no intimate 

 relation to each other, except as far as both belong to 



* Compare also Henfrey's remarks on the structure of the elaters of 

 Trichia, in Linn. Tr., vol. xxi., p. 221. 



