INTRODUCTION TO CRYPTOGAMIC BOTANY. 



431 



after the fashion of a mycelium, a perfect plant, which if 

 annual produces a single set of antheridia and archegonia 

 (Fig 89, c, d, e, &c.), or if of longer than annual duration a 

 new set for every year, except in those cases where the plant 

 does not arrive at maturity in the first season. There is, in- 

 deed, considerable diversity in the fruit thus produced, which 

 may consist of a simple sac, as in Riccia, immersed in the 



Fig. 89. 



a. Riccia Fluitans. nat. size, aud slightly magnified. 



b. Riccia natans, nat. size. Both received from Mr. E. Skepper. One 

 specimen has lost all its fringe. 



c. Archegonium of Riccia glaioca in an early stage of growth, ver- 

 tical section. 



d. Ditto with embryonic cell just ready for impregnation. 



e. Vertical section of very young autheridium. These three figures 

 are borrowed from Hofmeister.* 



substance of the frond, of a similar sac, raised above the surface 

 upon a peduncle, and covered with one or more envelopes, as in 

 Jungermannice ; these sacs again may })e collected into groups, 

 and disposed symmetrically on distinct pedunculate organs, 

 as in Marchantiw, or the organ which contains the spores may 

 be still more complicated, bursting by a horizontal fissure and 



* Vergleichende TJntersuchungen der Keimung, Entfaltung und 

 Fruchtbildung hoherer Cryptogamen. W. Hofmeister, Leipz., 1851. 

 Consult also Unger in Linn., v. 13, p. 1, on the development of Riccia 

 glauca. 



