546 



PHANEROGAMS. 



the result of the lateral coalescence of two stamens. In this case the filaments 

 become combined into a central column, on which (as is shown in Fi^. 368, ///) the 

 pollen-sacs grow more rapidly in length than the filaments, forming vermiform coils. 

 The relationships are much more complicated and more difficult to understand 

 when cohesion and branching of the stamens occur simultaneously, as in Mal- 

 vaceae. In Althcp.a rosea, for instance, the filaments form a membranous closed 

 tube which completely envelopes the gynaeceum; springing from this tube are five 

 vertical and parallel double rows of long filaments, each of which (Fig. 369, B) 

 again splits into two arms (/), and each of these arms bears a single anther-lobe. 

 The history of development and a comparison with allied forms shows that the tube 

 is formed by the lateral coalescence of five stamens ; but the coherent margins produce 

 double rows of lateral ramifications, in other words, of filaments, which then again 

 split into two arms. A horizontal section of the young staminal tube (Fig. 369, A) 

 shows plainly these double rows of split filaments ; the part {v) which lies between 

 two of these must be considered as the substance of a stamen, the margins of which 



Fig. 369 — Althaa rosea; A horizontal section through the young andrcecium ; K a piece of the tube of a mature 

 androecium with several stamens ; h cavity of the tube, v substance of the tube, a anthers, t the spot where the 

 filament divides, /"the spot where two filaments spring from the tube (A much more strongly magnified than B). 



each bear right and left a simple row of filaments as lacinias or branches ^ In 

 the Lime, where the five primordial stamens also branch at the margins, and form 

 anthers on their branches, the stamens remain free, but in other respects the 

 phenomena are altogether similar [cf. Payer, /. <r.) 



The stamens not unfrequently suffer conspicuous displacements by the inter- 

 calary growth of the tissue of the receptacle in the region of their insertion ; and 

 such displacements are also ordinarily included under the term cohesion (or adhe- 

 sion)^. Thus the stamens often adhere to the calyx or corolla; and then, when 



' The strangeness of this conception will disappear if the structure is recalled of a unilocular 

 ovary with numerous carpels coherent at the margins, e. g. Viola, where the ovules arise in double 

 rows on the lines of junction (^the placentae). What takes place in one case in the inside in reference 

 to the ovules takes place in the other case on the outside in the formation of the filaments. 



^ [It has come to be the usage in English works on descriptive botany to apply the term 

 ' cohesion ' to the apparent union of organs of the same kind, ' adhesion ' to the apparent union of 

 organs of a different kind.] 



