CHAP, ii i The Morphology of the Flower 91 



aril. The ovaries are naked, and each contains a single 

 orthotropous ovule on a basal placenta, the ovary wall 

 being adherent to the ovule. This hypothesis was sup- 

 ported in 1869 by Sperk, and in his earlier writings of 1872 

 by Strasburger, though later (1879) ne came to consider 

 the so-called ovary to be an ovule. 



The view which on the whole met with the most 

 general acceptance was put forward by Sachs in the first 

 edition of the Lehrbuch in 1868, and was in 1881 endorsed 

 and amplified by Eichler. In their opinion the cone of 

 Pinus is a single flower consisting of an axis with numerous 

 seminiferous scales arranged spirally along it ; each scale is 

 a carpel, from the face of which an outgrowth of the nature 

 of a placenta is developed, and on this placental scale or 

 ligule, two naked ovules are seated. Eichler said that this 

 structure occurs in the Araucariae, the Abietineae and the 

 Taxodineae. The Cupressineae bear their ovules in the 

 axils of the carpellary scales. Taxus and Torreya bear 

 them at the apices of lateral shoots, the apex becoming 

 modified into the ovule, and carpels being absent. They 

 are surrounded by an aril. In these two genera conse- 

 quently the flower is represented by a solitary ovule. 



A theory in many respects resembling the views of Braun 

 was advanced in 1869 by Van Tieghem. The scale is a 

 foliar organ, the first and only leaf of an axis which arises 

 in the axil of the carpellary scale or primary bract, and 

 undergoes no further development. Arising from this 

 suppressed axis its face is turned towards the primary bract 

 and it bears the two ovules usuallv on its dorsal surface, 



v/ 



just as the microsporangia are borne upon the dorsal surface 

 of the leaf-like stamens in the male flowers. In the 

 Taxineae the ovules terminate the carpellary leaf ; they 

 result from the transformation of its whole entire limb, or 

 as in Ginkgo and Cephalotaxus, from a similar transformation 

 of each half of the limb. In other words, the carpellary 



