424 PROF. OLIVER ON THE STRUCTURE OF THE ANTHER. 



that the anther results from a metamorphosis of the lamina of the leaf*. Erom the 

 examination of a transverse section of the form of anther generally prevailing in flower- 

 ing plants, in its young state and prior to the absorption of the vertical septa which pass 

 from the connective through each lobe, thus rendering it four-celled, it may reasonably 

 be supposed that the margins of these septa, answering to the longitudinal sutures and 

 lines of dehiscence of the anther, correspond likewise with the margins of the lamina of 

 the stamen-leaf — the septa, however, being plates of untransformed tissue of uncertain 

 homology. The opinion that the sutures of the anther correspond to the margins of the 

 leaf, and that the pollen-cavities, separated by the septa of unchanged tissue, originate 

 in its parenchyma, was advanced, according to Von Mohl, by Cassinif ; and the same view 

 has been maintained by Roeper|, Schlechtendal§, Grisebach, and others. Among 

 botanists holding this opinion, who have recently expressed themselves definitely upon 

 the subject, I find Prof. Grisebach, in. his " Grundriss d. syst. Botanik"||, says, "The 

 layers of the anther in which the pollen is formed answer to the four parenchym-layers 

 of a leaf, in which the midrib and the vascular bundles correspond, in respect to their 

 situation, to the parenchymatous septa in the anther between the pollen-originating 

 layers." Dr. Asa Gray, in his ' Introduction to Botany ' (1858)'[r, says, " A transverse 

 section of the forming anther shows four places in which the transformation of the 

 parenchyma into pollen commences, which answer to the centre of the four divisions of 

 the parenchyma of a leaf, — viz., the two sides of the blade, distinguished into its upper 

 and lower stratum. So that the anther is primarily and typically four-celled, — each lobe 

 being divided by a portion of untransformed tissue, stretching from the connective to the 

 opposite side, which corresponds to the margin of the leaf and the line of dehiscence." 

 And further, " Viewed morphologically, therefore, the filament answers to the petiole of 

 a leaf, the anther to the blade ; the connective represents the midrib, the lobes or cells of 

 the anther represent the two symmetrical halves of the blade, and the line of dehiscence 

 is normally along the margins of the transformed leaf." Dr. Lindley, in ' Introduction 

 to Botany**,' says, "The line of dehiscence in ordinary circumstances is the margin of 

 the modified leaf." Neumann, in the paper before referred to, upon anticous and pos- 

 ticous anthers, expresses the opinion very decidedly that the anterior and posterior 

 cells of each anther-lobe correspond to opposed strata of the metamorphosed leaf, and 

 that the suture answers to its margin. Somewhat difierent from the foregoing is the 

 theory of Bischoff ft- He maintained that the suture of the anther does not correspond 

 to the leaf-margin ; that the loculaments develope upon its superior sm'face, within the 



* He says, referring to these monstrous stamens, " Cependant ces antheres, .... n'ont pas en ge'neral la 

 structure anatomique propre a ce systeme d'organes. Aiusi le plus souvent les renflements ne presentent pas des 

 points ou la eouclie fibreuse interrompue pourrait permettre la libre sortie du pollen. Cependant on voit dans la 

 figure .... que la couche fibreuse tres-amincie en a [this refers to a cross-section of one of the anthers, showing a 

 thinning at the collateral junction of the lobes] semble inviter la lobe a s'ouvrir." Somewhat similar abnormal 

 anthers from the Rose are figured by Kaspail (Me'ra. Soc. d'Hist. Nat. Paris, iii. tab. 2, 4.5-6). 



t Opus. Phytol. ii. p. 551. t Enum. Euphorb. p. 4-4. 



§ Linnaja, i. (I82C), p. 602. In " Obs. on Monstrosity of a Garden-Tulip." 



Ii (1854), p. 40. II Pp. 284-5. 



'** Ed. 4. i. p. 349. tt Lehrbuch, i. 334. 



