1901.] 



NATURAL SCIEKCES OF nilLADELPHIA. 



311 



tlie coutrolliug influence in regulating the size of dorsiventral 

 organs, such as foliage leaves, has been abundantly proven. The 

 measurements presented in Table III will at some future time be 

 compared with those obtained from seedling plants, so as more 

 clearly lo present statistically the similarity of the youngest and 

 oldest leaves of the normal shoot and the juvenile ones of the 

 seedling tree. 



Table IV presents the statistical study of the leaves of a normal 

 shoot taken from a tree growing at Raven Rock, Pa. In compar- 

 ing the figures of this table with those of Table III, it is necessary 

 to read from the bottom up, leaf No. 7 of Table IV being com- 

 pared with leaf No. 1 of Table III. 



The leaves obtained from sprouts growing from a stump were out 

 of all proportion to the size of the leaves on normally produced 

 shoots. Table V shows the largest of the leaves studied to be .370 

 mm. long and .432 mm. wide. A comparison also of the leaves of 

 the sprouts Avith each other indicates that a very considerable vari- 

 ation occurs. By contrasting these sprout leaves with normal ones, 

 the limits of the variations in this one plant are clearly set forth. 

 Variations which are due to the reversion of the sprout leaves to 

 the juvenile forms on the seedling plants, however, enormously 

 increased in size. It should be mentioned, also, that the stipules 

 of the leaves on the sprouts are correspondingly increased in size, 

 are permanent and assimilative, not caducous, as the small stipules 

 of normal leaves. Measurements of these stipules are also given: 



///. Fresh Leaves of Liriocletulron tulipifera {two terminal shoots count- 

 ing from bctse to apex). 



Second Shoot. 



