BOTANICAL SUBJECTS. Ill 



much stretch of the imagination, not only with land ferns, but also 

 with the higher phsenogams, or \ what are commonly called 

 flowering plants. It should not be forgotten that while in phseno- 

 gams colour and great variation of form are oftener limited to the 

 flower, in seaweeds the whole plant may be coloured, as we see 

 it in Coleus, Caladium^ and others. 



It is enough to glance over any work on seaweeds, such as 

 " Harvey's Phycologia Britannica," or " Australica," to obtain an 

 idea of the gradual complexity of cell aggregation and growth, 

 which has occurred if not in the whole plant, certainly in its parts. 

 Nothing, in my opinion, can give us a clearer conception of evolu- 

 tion than the contemplation of these organisms. "We seem to see 

 most of the types of land plants foreshadowed in these simple 

 metaphyta. 



It must not be supposed that because phycologists and other 

 cryptogamists have given various names to all the parts of these 

 cryptogams that therefore they are not really homologous with the 

 different parts of the higher land plants, and essentially the same 

 taings. 



From simple cells we can pass to simple aggregates of cells, 

 such as in Monormia intricata* The cells in this are disposed 

 in threads, and some of the component cells are already differ- 

 entiated for special functions. Lynghia flacca] has, in addition, 

 the evolution of hairs, or roots, or leaves, or branches. Calo- 

 thrix ccespitula% is made up of cellular threads which at first are 

 independent and afterwards reunite as parasitic branches, like the 

 Cladothrix dicliotoma of Dr. Klein. In Calothrix fasciculata\ 

 the parasitic branches adhere round a certain point so as to 

 resemble the leaves of certain fan -palms. In the hairs of Calo- 

 thrix luteola\\ and C. confervicola^ we get distant adumbrations 

 of the pines and horsetails. In Porphyra vulgaris** we have 

 aggregations of cells in tapes, or leaf-like expansions, such as we 

 find in many ferns. In this seaweed we have the development of 



* " Harvey's Phycologia Brit.," v. 4, pi. 256. 



t » „ pi. 300. 



i » „ pi. 305. 



§ » ,5 pl. 58a. 



II „ ,, pl. 342. 



IT „ „ pl. 254. 



** « ,' pl. 211. 



