io8 



Elementary Biology. 



FIG. 40. - -TRANSVERSE SECTION 

 THROUGH THE SPORE-SAC OF 

 Funaria hygrometrica. (Sachs.) 



explaining the homologies of the various parts begins. On 



fertilisation the ovum becomes an embryo. The canal 



cells are now completely disorganised and disappear. The 



embryo rapidly divides and forms a mass of cells which soon 



differentiates into a stalk, or 



seta, and a capsule, or theca. 



As the development of this 



organism takes place in the 



venter, naturally the venter 



very soon becomes too large 



to contain it, and its walls give 



FIG. 35. Funaria. hygrometrica. 

 (Sachs.) 



A, female plant, with root hairs, and young 

 theca enclosed in the calyptra, c. B, 

 asexual generation nearly mature ; s, 

 seta ; J\ iheca. C. longitudinal section of 

 theca (magnified) ; tec, columella ; d, 

 operculum ; /, peristome ; s. archespo- 

 riam ; h, air-spaces. 



A, sit, archesporium. B, s i, 

 mother spore-cells ; a, outer, /', 

 inner side of the spcre-sac. 



way at the base, whilst the embryo bears on its head, or 

 theca, the upper portion of the venter and its neck as a cap, 

 or calyptra. The calyptra remains attached to the embryo 



