256 THE AMERICAN NATURALIST. [Vol. XXXVII. 



three lobes and tri-nerved. The next leaf is more decidedly tri- 

 lobed but with a division into teeth. The next leaf has the lower 

 lobes divided and this division becomes somewhat more marked 

 in later leaves until the most complicated leaf is developed as in 

 leaf 7, Fig. 42. In Fig. 44 is shown a leaf intermediate between 

 leaves 1 and 2 of Fig. 43. By obtaining more specimens a more 

 complete series may be secured between many of the stages. In 

 Fig. 43 a significant thing is shown in the size of leaf 2. The 

 first leaf grew under unfavorable conditions and its development 

 in size went but a little way. The weather changed however 

 and became wanner while leaf 2 was developing and its unusual 

 size is the result. Next it was colder and leaves 3 and 4 felt 

 the effect. This was noticeable in many cases at 

 this particular time. 



Turning to the flower Fig. 45, the leaves are 

 reduced as shown in the lowest leaf figured to 

 leaves corresponding to Fig. 43, leaf 1. But as in 

 the cases mentioned before, the reduction is carried 

 still farther as leaf 2 is simple 111 outline with no 

 traces of the teeth or lobes of the simplest leaf of 

 spring growth. This simpler form is found in a great number 

 of cases in the last leaf below the flower. As in cases previously 

 mentioned this stage is simpler than in its own young. 



