146 



PHILOSOPHICAL NOTES ON 



original form. The leaflets (a) remain, (6) are aborted into glands 

 similar to the petiole glands of apricots, cherries, &c. and (c) are 

 aborted into stipels. 



4. A Spircea had the form of leaf shown in diagram. Fig. 30— (a) 



Fig. 30. 

 were sessile, (&) petiolated, (c) secondary sessile leaflets, and (d) 

 only a lohe of the odd leaflet. This shows how unimportant the 

 forms of leaves are, except as a means of identifying plants for 

 economical and other purposes. They are elastic, as if it were. 

 They can either spread out, and form independent petiolated leaflets, 

 or contract into separate sessile, or eren into lobed laminee. If 

 this Spircea leaf were shortened, it might assume something of the 

 form of the Erythrina leaf. It also shows that a lobe of a leaf is 

 interchangeable with a secondary leaflet, as in the variegated maptle, 

 raspberry, and others ; and that it may be no other than a main 

 tooth, and the toothlets no other than abortiye leaflets. 



Fig. 31. Margin of Spiraa leaflet; (a) abortive secondary leaflets, 

 (6) abortive tertiary '^leaflets, (c) midrib of entire leaflet. 



