92 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Sek. 



suckers would be found which retain this primitive charac- 

 ter for considerable periods, if not throughout their exis- 

 tence. If Goebel's other supposition is true — that the basal 

 branches, showing the young form of leaves, disappear by 

 correlation as the mature form develops — one would infer 

 the greater physiological perfection and effectiveness of 

 the mature as compared with the young form. But in the 

 white suckers the main function of leaves, that of photosyn- 

 thetically manufacturing non-nitrogenous food, is entirely 

 suppressed — the mature form of white leaves being as im- 

 potent as the young form. Two other important functions 

 of leaves — that of securing and controlling transpiration, 

 and that of securing and controlHng the aeration of the 

 plant-body, — would apparently be as perfectly prepared for 

 and accomplished b}^ the one form of leaves as the other, 

 provided the texture and the surface-area of the two kinds 

 of leaves are equal. In these two respects the mature 

 leaves are superior to the young form. There is, therefore, 

 some reason, other than the conception of an "inherited 

 tendency," for the development of the mature form of 

 leaves in the white suckers. 



Since the Sequoias are geologically such old plants, it is 

 interesting to have the young form of leaves so clearly 

 marked and so constantly recurring. There is a striking 

 resemblance between some of the green suckers in their 

 young condition and the great fronds of Cycas revoluta, the 

 leaves of the redwood resembling the leaflets of Cycas in 

 form, thickness and arrangement. Can this be a hint as to 

 the origin, perhaps the common origin, of the Coniferas and 

 the Cycadaceae ? 



Comparing the mature form of leaves of green and of 

 white suckers from the same localities, one finds that, 

 despite the superficial Hkenesses, there are decided struc- 

 tural differences. These are at once evident in cross- 

 sections of the leaves, as shown in figs, i and 2. Figure 1 

 is a diagram of a cross-section of a small green redwood 

 leaf, the single vascular bundle occupying the centre of the 

 leaf, one resin-tube lying under it, the other two resin-tubes 



