ON STIPULES 43 



I now come to the stipuliform appendages. These 

 often bear honey-glands, bnt by no means always, and 

 even where these occur there seems no reason why 

 they should be situated on filiform appendages. On 

 the whole, then, I doubt whether they can be explained 

 as mere honey-glands, or whether, indeed, they are of 

 any actual use when the leaves are fully developed. 



When we meet with a small organ which appears 

 to have no definite function, we naturally ask ourselves 

 whether it is the disappearing relic of some larger 

 organ which at one time performed some useful pur- 

 pose in the economy of the animal or plant. This 

 suggestion, however, seems untenable in the present 

 case, because, as a matter of fact, we do not find that 

 the stipuliform appendages are more developed in any 

 of the species allied to V. Opulus. 



There is, however, a physical cause to which, per- 

 haps, the presence of these organs may be due. We 

 have seen that much the larger number. of species of 

 Viburnum have entire leaves, more or less oval or 

 ovate. This would appear to be the form typical or 

 original to the genus. 



Now let us suppose that, either from having extended 

 northwards (and both Viburnum Lantana and V. Opulus 

 are among the northern representatives of the genus), 

 or from some other cause, the young leaves require 

 additional protection. This may be effected in several 

 ways. For instance, the young leaf may be guarded 



