HEPATICJS. 



347 



by the rajDid growth of the surrounding tissue of the 

 {A, B, iind G, 



Fig. 232). In ^>r^r^,"A 'J^^&i'''' tm^nr 

 other cases the 

 antheridia are de- 

 veloped in great 

 numbers upon 

 special branches, 

 as in Marchantia, 

 which has a large 

 "anthevidialdisc" 

 {A and B, Fig. 

 231, Ml), in whose 

 upper surface are 

 to be found many 

 imbedded anther- 

 idia. That tlie an- 

 ' theridia are actu- 

 ally external in 

 this case also, be- 

 coming apparent- 

 ly internal by, the 

 growing up of the 

 surrounding tis- 

 sues, is well shown 

 in Fig. 233. In 

 still other cases 

 {e.g., in Junger- 

 mamiiacecB) the 

 antheridia are in 

 the axils of the 

 leaves, and occur 

 singly or in groups. 

 453.— The ar- 

 chegonium first 

 appears as a simple 

 papilla, composed 

 of a single cell, 

 which, by subdi- 

 vision in va"'ous 



thallus 



Fig. 335. — The archegonia, and origin of the sporojjo- 

 nium otMarchaniia polijmorpha. /. and //. , yonng arche- 

 gonia ; e, germ cell ; si, lowest cell of axial row of cells. 

 111. and IV., the same iifter the formation of a central 

 canal by the absorption of the axial row of cells in the 

 neclc. v.. the same when mature and ready for fertiliza- 

 tion. 77., the baj^e of a fertilized archegonium. the 

 germ-cell,/, divided into two cells by a diagonal partition. 

 Vll.i later stage of the same, showing further division of 

 the germ-cell, /. and the beginning of the growth of a 

 perianth, pp. YIII., still later stage of the same, the 

 perianth, pp, now enclosing the archegonium ; x. the 

 witlierea neck of the archegonium. IX., the unripe ejioro- 

 gonium, enclosed in the old walls of the archegonium,. 

 now called the calyptra, a ; /, wall of sporogonium ; 

 »t, the short, undeveloped stalk of the sporogonium. 

 Inside of the sporogonium are the young elaters arranged 

 radially, and between them are the spores. I. to VIII.. 

 X 300 ; IX. about SO.— Alter Sachs. 



directions, gives rise to a more or less 



