BOTANICAL SUBJECTS. 



345 



Fig. 149. Citrus caipels iu young stage (Payer, pi. 25) : (a) staineiip, 

 (6) carpels, (c) outer margin of disk, which in the lipe flower becomes the 

 di^^k proper, (rf) peel hark, which the caqjels are cariying with them. 



Fig, 150. Pistil of Citrus with the disk jnoper (c) (Payer, pi. 25). 



Supposing now thfit tlicsc lioiii<> Mere developed into active 

 leaves, they would receive Hbro-vnscular bundles as other leaves do 

 but as they continue to function simply as harh, they can dispense 

 with them and remain wholly cellular. 



We see similar phenomena in the atrophy of other parts, such 

 as the toothlets on the tooth of a Primula leaf, Fig. 151. If this 

 tooth were to become further atroi)hied, the subordinate teeth 

 would ichoUy disappear, and the whole main tooth would be 



