37^ 



VASCULAR CRYPTOGAMS. 



CLASS VIII. 



OPHIOGLOSSACE.^^ 



The Sexual Generation. The prothallium is at present known only in Ophio- 

 glossum pedimculosum and BoUychium Lunaria. In both cases it is developed 

 underground. It is destitute of chlorophyll, and forms a parenchymatous mass of 

 tissue which, according to Mettenius, has at first, in the species first-named, the 

 form of a small round tuber, out of which is subsequently developed a cylindrical 

 vermiform shoot, which grows erect underground, is rarely and slightly branched, 

 and elongates by means of a single apical cell. When the apex appears above 



Fig. iZi.—Botrychhim Lunaria; A longitudinal section of protliallium (Xso), ac an archegoniiim, an an anthcri- 

 diuin, iv root-hairs; B longitudinal section of the lower part of a young plant dug up in September (X20) ; st stem, 

 b b' b" leaves (after Hofmeister). 



ground and becomes green, it forms lobes and ceases to grow. The tissue of 

 this prothallium is differentiated into an axial bundle of elongated, and a cortex of 

 shorter parenchymatous cells, and the surface is clothed with root- hairs. With 

 a transverse diameter of 4 to i^ lines, it attains a length of from 2 lines to 

 2 inches. The prothallium of Boirychiu??i Lunaria is, according to Hofmeister, 

 an ovoid mass of firm cellular tissue, the greatest diameter of which does not 

 exceed h line, and is often much less (Fig. 281, ^). It is light brown externally, 

 yellowish white internally, and provided on all sides with sparse moderately long 

 root-hairs. These prothallia are monoecious ; each one produces a number of 

 antheridia and archegonia, which are distributed with tolerable uniformity over the 



^ Mettenius, Filices horti botanici Lipsiensis. Leipzig 1856, p. 119. — Hofmeister, Abhandlungen 

 der konigl, Sachs. Gesellsch. der Wissens. 1857, p. 657. — [On the Gennination, Development and 

 Fructification of the Higher Cryptogams, Ray Soc. 1862, pp. 307-317.] — On the probably near rela- 

 tionship between this class and Marattiaceee, see p. 361. 



