202 METAMOKPHY. 



tending to show that the anther is in such cases really 

 a modification of the blade of the leaf; but as, on the 

 other liand, we often find petal-like filaments bearing 

 pollen-sacs on their sides, it is clear that we must not 

 attribute the formation of pollen to the blade of the 

 leaf only, but we must admit that it may be formed in 

 the filament as well.^ 



^ Although it is generally admitted that the filament of the stamen 

 coiTcsponds to the stalk of the leaf, and the anther to the leaf-blade, yet 

 there are some points on which uncertainty still rests. One of these is 

 as to the sutures of the anther. Do these chinks through which the 

 pollen escapes coiTCspond (as would at first sight seem probable) to the 

 mai'gins of the antheral leaf, or do they answer to the lines that separate 

 the two pollen-cavities on each half of the anther one from the other ? 

 Professor Oliver, ' Trans. Linn. Soc.,' vol. xxiii, 1862, p. 423, in alluding to 

 the views held by others on this subject, concludes, from an examination 

 of some geranium flowers in which the stamens were more or less petaloid, 

 that BischoflTs notion as to the sutures of the anther is correct, viz., 

 that they are the equivalents of the septa of untransformed tissue 

 between the pollen-sacs. Some double fuchsias (' Gard. Chron.,' 1863, 

 p. 989) add confirmation to this opinion. In these flowers the petals 

 were present as usual, but the stamens were more or less petaloid, the fila- 

 ments were unchanged, but the anthers existed in the form of a petal-like 

 cup from the centre of which projected two imperfect pollen-lobes (the 

 other two lobes being petaloid). Now, in this case, the margins of the 

 anther were coherent to form the cup, and the pollen was emitted along a 

 line separating the poUiniferous from the petaloid portion of the anther. 

 This view is also borne out by the double-flowered 

 Arbutus Unedo, and also by what occurs in some 

 double violets, wherein the anther exists in the 

 guise of a broad lancet-shaped expansion, from 

 the surface of which project four plates (fig. 157), 

 representing apparently the walls of the pollen- 

 sacs, but destitute of pollen; the chink left be- 

 tween these plates coiresponds thus to the suture 

 of the normal anther. 



The inner or upper portion of the anther-leaf 



is that which is most intimately concerned in the 



formation of pollen ; it comparatively rarely 



(query ever) happens that the back or lower 



1? n;'7 T> surface of the antheral leaf is specially devoted 



1 A {^'"^^^'f. to the foi-mation of poUen. On the other hand, 



V'l ^^if^f "^ ^^^^^ ^^^ *^^ ^^ *^^ common houscieek, 



Kioto, witn four ,^}iere we meet with petaloid organs combining 

 projecting plates. ^^le attributes of anthers and of carpels, we find 

 the inner layers devoted to the production of pollen, 

 the outer to the formation of ovules. 



That the pollen-lobes are not to be taken as halves of a staminal leaf, 

 but i-ather as specialised portions of it, not necessarily occupying half 

 its surface, is shown also in the case of double-flowered Malvacetp, in 

 which the stamens are frequently partly petal -like, partly divided into 



