14 



BOTANY 



PART I 



The Cormus. — All plants the body of which can be regarded as 

 a tliallus are grouped together as Thallophytes, and contrasted with 

 Cormophytes in Avhich a shoot is developed. The latter include two 

 developmental series which, though assumed to have had a common 



cCV*^ 



1 -^ 



Fig. 10. — Riccin Jliiitans. 

 (Nat. size.) 





Fio. Il.—Blasia pnsilla. s, Sporogonium ; 

 r, rhizoids. (x 2.) 



Starting-point, have attained a cormophytic organisation independently. 

 These two groups are the moss-like plants or Bryophyta and the 

 Pteridophyta including the ferns and their allies ; from the Pterido- 



phyta the seed-plants, the highest group 

 in the vegetable kingdom was derived. 

 Among the Bryophytes forms occur, as in 

 some groups of Liverworts (Hepaticae), 

 with a completely thalloid body which is 

 ribbon-shaped and only exhibits an imper- 

 fect differentiation into members. Thus 

 Eiccia fluitans (Pig- 10) is ribbon-shaped 

 and dichotomously branched, and its habit 

 or general appearance recalls the Brown 

 Alga Didyota dichotoma mentioned above 

 (Fig. 8) as an example of a thallus. Blasia 

 pusilla (Fig. 11) has marginal indentations 

 in its ribbon-shaped body. Lastly, Flagio- 

 chila asplenioides (Fig. 12), another Liver- 

 wort, has a distinction of stem-like and 

 leaf -like members which is completely 

 analogous to that exhibited by the most 

 highly organised plants. 



In addition to the distinction of stem 

 and leaf in their .shoots, the Pteridophyta possess true roots, while 

 even the most highly oi'ganised Bryoi)hyta have only filamentous 

 structures (rhizoids) (Fig. 11 r) in place of roots to attach them to 

 the substratum. True roots, on the other hand, which appear for 



Fl«i. \2.—Pla{iiochUii. asplenioides. 

 g, siiorogonium. (Nat. size.) 



