282 PHILOSOPHICAL NOTES ON 



The prickles on the rose-stem are not usually tipped with a 

 pin-head, nevertheless, they are mere exaggerations of the stalk of 

 the glandular hair, for on the midrib of the young leaflets the 

 prickles are now and again tipped with a gland. The prickles 

 become changed into glandular hairs,* as shown in Fig. 115. 



L± 



Fig. 115. Prickles changing into glandular Fig. 116. Teeth of Rose leaf, 

 hairs on the midrib of the Rose leaflet. The lower ones with glands, 



the upper with only points. 



These appear to be only repetitions of the teeth of the rose leaf, as 

 shown in Fig. 116. The point of the prickle and the point of 

 the tooth are only atrophied and modified glands ; the gland of 

 one tooth either atrophies, or is modified into the point of another 

 tooth. 



According to this \dew, we may consider the tooth as a glandu- 

 lar hair, with a foliaceous stalk. But this we also find on the 

 stem of the moss-rose. There we find branched glandular hairs, 

 with their common stalk flattened and foliaceous. They do not 

 differ in structure from teeth, and have vessels projecting into 

 them, as teeth have. In the moss-rose we find many of the leaf- 

 teeth tipped with globular glands ; on the margins of the teeth are 

 rows of glandular hairs, representing minor teeth. The sepals of 

 the moss-rose are one mass of branched foliaceous prickles, each 

 tipped with a gland, and the branches become re-branched, each 

 branchlet being tipped ^vith glands. 



It is impossible to look at the margin of a moss-rose leaf, 

 through a lens, and not be convinced that the main teeth of the 

 bud-scales, stipules, and leaves are nothing but branched glandu- 

 lar hairs, and that the minor teeth are simple glandular hairs, like 

 those on the stem and sepals. We would then be justified in 



* This is plain in the yellow Scotch rose and in the dog rose of the 

 hedges. 



