BOTANICAL SUBJECTS. 



123 



Fig. 16. Gigartina lanceolata ("Har\\ Phyc. Austr.," pi. 288) — portions 



of cladophyls. 



The reader who is imbued with the spirit of the evolutionary 

 theory will see that in these seaweeds we have rudimentary stages 

 of the stem, midrib, lamina, and other parts of the stem and leaf of 

 phsenogams. They are so simple in their structure because the 

 medium in which plants commenced their evolution did not 

 necessitate a more complicated structure. 



"We must try and get rid of the artificial and antiquated 

 distinction of cryptogams and phasnogams. If we accept the 

 theory of evolution, the only meaning we can apply to them is 

 analogous to that of stone and steel as applied to the evolution of 

 a knife or axe. If we cannot find any sufficiently satisfactory 

 links between these two so-called divisions of the vegetable king- 

 dom, it may be either because they have disappeared or because 

 there is no such thing as a gradual transition between plants 

 inhabiting two so distinct media as water and air, unless they be 

 those which inhabit swamps or a moist atmosphere, such as filmy 

 ferns can live in. 



In many species of Ranunculus, such as R. aquatilis, we find 

 that the submerged leaves have no epidermis. The moment its 

 leaves are born into the air they have an epidermis. Therefore, 



