STRUCTURE.] STIGMA ITS NATURE. 3C7 



The stigma is the upper extremity of the style, without 

 epidermis ; in consequence of which it has, almost uniformly, 

 either a humid or papillose surface. In the first case it is so 

 in consequence of the fluids of the style being allowed to flow 

 up through the intercellular passages of the tissue, there 

 being no cuticle to repress and conceal them ; in the latter 

 case the papillae are really the rounded sides of vesicles of 

 cellular tissue. When perfectly simple, it is usually notched 

 on one side, the notch corresponding with the side from 

 which the placenta arises : see the stigma of Rosa, Prunus, 

 Pyrus, and others. If it belongs to a single carpel, it is 

 either undivided, or its divisions, if any, are placed side by 

 side, as in Spurgeworts (Euphorbiacese), Crocus, &c. ; but if 

 it is formed by the union of the stigmas of several carpels, 

 its lobes are either opposite each other, as in Mimulus, or 

 placed in a whorl, as in Geranium. Such being the case, it 

 is a general law that an apparently simple ovary, to which 

 more than two opposite stigmas belong, is really of a compound 

 nature ; but, when the stigma of a simple carpel is two-lobed, 

 the arms are often placed exactly opposite each other, as in 

 Composites, Grasses, &c., and then the apparent number of 

 the stigmas is not the real number. 



Dr. Robert Brown has the following observations on 

 this subject: "On the subject of the origin and type of 

 Stigma, my first observation is, that the style, where present, 

 can only be regarded as a mere attenuation, in many cases 

 very gradual, of the whole body of the ovarium. Hence the 

 idea naturally suggests itself, that the inner margins of the 

 carpel, which in the lower part are generally ovuliferous, in 

 the upper part perform the different, though in some degree 

 analogous, function of stigma. As the function, however, 

 of this organ implies its being external, and as in different 

 families, genera, and even species, it has to adapt itself to 

 various arrangements of parts destined to act upon it, cor- 

 responding modifications of form and position become neces- 

 sary ; hence it is frequently confined to the apex, and very 

 often, especially in the compound ovarium with united styles, 

 appears to be absolutely terminal. 



In such cases, as it must always include and be closely 



