LINNEAN SOCIETY OF LONDON. 127 



space, these leaves are folded more or less like a fan, in the same 

 manner as those of Maples, Sycamores, Planes, &c, and this gives 

 them their lobed form. As regards the stipuliform appendages, the 

 genus contains some fifty species, of which about forty have oval 

 leaves without appendages, while the remainder have lobed leaves 

 with appendages. The presence of these appendages seems, there- 

 fore, to go with that of the lobes. I believe that they assume that 

 peculiar thread-like form so as to fill up a space which would other- 

 wise be left empty in the bud. Maples have no stipules, but in them 

 the younger leaves in the bud just fill up the interspaces left between 

 the older ones. In the lobed-leaved Guelder Koses this is not the 

 case, but a space remains, which is just occupied by the stipuliform 

 appendages. 



(4.) "On the Presence and Functions of Stipules." Vaucher, 

 in his ' Histoire Physiologique des Plantes,' speaking of Heli- 

 anthemum, says: — " J'indique dans ce genre deux principaux 

 objets de recherche. Le premier est la raison pour laquelle 

 certaines especes out des stipules, tandis que d'autres en sont 

 privees." No one, however, so far as I know, has yet attempted 

 to answer this question, which, however, is one of considerable 

 interest, and might be asked with reference to several other groups 

 besides the genus Helianthennim. In attempting to answer this 

 question, we may begin by considering the function or functions 

 which stipules perform. Of these, the primary purpose is to protect 

 the bud. In others they serve as accessory, or deputy, leaves. 

 As an illustration of the former may be mentioned some species of 

 Viola; of the latter, certain species of Lathyrus — for instance, 

 L. Nissolia. The question may further be asked, What is the 

 advantage to the plant in having the purpose of the leaves fulfilled 

 by stipules instead of true leaves ? Now, L. Nissolia is a species 

 which lives among grass. Here, then, the same considerations 

 which render it an advantage to grasses to have long leaves affect 

 equally the Lathyrus. Again, if, when so growing, the leaves of L. 

 Nissolia had resembled those of most other Lathyrus, they would, 

 perhaps, have been dangerously conspicuous. The similarity of the 

 stipules to the leaves of grasses by which they are surrounded 

 perhaps enables them to escape observation, and to avoid being 

 eaten. It may, indeed, be asked why the leaflets should not have 

 assumed the long linear outline. But, even so, if they had been 

 arranged at right angles to the petiole, the plant would have been 

 much less grass-like, and consequently much more conspicuous 

 than is now the case. This may, I think, be the reason which has 

 led to the replacement of leaves by stipules in this species, and to 

 the peculiar form which the latter have assumed. Passing on now 

 to the cases in which the stipules serve to protect the young leaves, 

 I may first mention in passing those instances in which the stipules 

 with this object have become stiff, pointed, or thorn-like, as in 

 Robinia. In far more numerous species, however, the stipules 

 protect by enveloping the young bud and leaves. In such groups 

 the view that the function of the stipules is mainly to protect the 

 young leaf is confirmed, not to say proved, by the fact that they are 



