PROBLEMS OF MODERN SCIENCE 



environment, and leaves for assimilation, has re- 

 mained until very recently a matter of speculation. 

 It was supposed that the transition from water to 

 land took place at such a remote epoch that direct 

 evidence of how it occurred could hardly be ex- 

 pected. Bower, in his classical work The Origin 

 of a Land Flora (1908), has considered the many 

 phases of this problem from the point of view of 

 comparative morphology. 



But recent discoveries, chiefly by Kidston and 

 Lang, from beautifully petrified material collected 

 by my colleague Professor Gordon in the Old 

 Red Sandstone of Rhynie, Scotland, have shown 

 that fossil material bearing directly on this problem 

 has long been at hand, but without the means for 

 its adequate interpretation. Recent discoveries in 

 Norway also bear directly on this question. The 

 remains at Rhynie consist of a silicified peat deposit 

 composed almost entirely of the stems and rhizomes 

 of a plant called by these authors Rhynia, in which 

 the structure is almost perfectly preserved. The 

 stems sometimes showed dichotomous (forked) 

 branching, but they bore neither roots nor leaves. 

 The rhizomes, however, bore primitive rhizoids, 

 no doubt functioning like those of mosses, and 

 the stems also had peculiar bulges or emergences 

 which later evolution may have developed into 

 leaves. The stems contained a simple conducting 

 system, and bore large terminal sporangia of a 



