364 A CENTURY Of PROGRESS IN THE NATURAL SCIENCES 



in this case, and had already in the lower permian led to the development of 

 wholly fertile seed-scale complexes. The evolution of the female conifer flower 

 presents some further features of interest. In some cases the number of sporo- 

 phylls was reduced to one, as seen in Lehachia, but usually there were at least 

 two sporophylls to each flower. The sporophylls themselves became more and 

 more reduced, and finally became completely incorporated in the "ovuliferous 

 scale." Various other parts became fused, e.g., the sterile scales along their mar- 

 gins, the sporophylls at their bases, and the "ovuliferous scale" to the bract. The 

 ovules were always orthotropous, seated singly and terminally on lateral mega- 

 sporophylls. They were first erect but from the upper permian onwards mostly 

 inverted. The female cones of living conifers are directly connected with those 

 of the mesozoic and paleozoic types. Disregarding such changes as a shortening 

 of the internodes of the cone axis and a reduction in the number of its append- 

 ages, the great morphological diversity in the female sex is due to the modifica- 

 tion in various directions of the axillary fertile short shoot and its accompany- 

 ing bract. The comparative study of living conifers disclosed additional trends 

 involved in the evolution of the female conifer cone, relating to external as well 

 as anatomical features. The genera Palaeotaxus, of early mesozoic age, Taxus, 

 ranging from mesozoic to recent times, and other still living taxads differ, how- 

 ever, from all true conifers by having solitary flowers. Their ovules are seated 

 terminally, on the flower axis itself, and megasporophylls are accordingly absent. 

 The flowers of these genera can therefore not be derived from those of the paleo- 

 zoic cordaites or conifers. 



Hirmer (1941), Wilde (1944), P. Bertrand (1947), Lam (1948, 1952), Gaus- 

 sen (1948, 1944-1952), Wilde and Eames (1948, 1952), as well as Magdefrau 

 (1942) — a former supporter of the excrescence theory — were convinced of the 

 correctness of the brachyblast conception of the female conifer cones (cf. Eames, 

 1913). Lam considered these stachyosporous by nature, while in the majority of 

 genera the male organs are phyllosporous. He also admitted that Taxus stands 

 apart from the true conifers, but did not consider the differences fundamental. 

 According to Wilde and Eames (1948), evidence of vascular anatomy supports 

 the view that the single ovule on the cone scale of Araucaria Bidwillii is a sur- 

 vivor of three, and that this cone may be derived from the mesozoic ScJiizolepis 

 type. Janchen (1949) appears to prefer Wettstein's and Herzf eld's view of the 

 nature of the ovuliferous scale. Besides Florin (I.e.), Plarris (1932, 1937, 1943), 

 Horhammer (1933), Hirmer and Horhammer (1934), Krausel (1938, 1952), 

 Kon'no (1944), Wieland (1935), and others, have studied the morphology of 

 various female conifer cones of mesozoic age. Elatides Williamsoni was shown 

 by Harris to be a member of the Taxodiaceae, the oldest yet known, and typical 

 araucarian cones were also found. 



Studies of the conifer male organs have been carried out by Goebel (1932), 

 Doyle and O'Leary (1934), Dluhosch (1937), Thomson (1940), Florin (1938- 

 1945, 1951), and Wilde (1944). The paleozoic genera differ from the cordaites 

 by the flower axis bearing in its fertile region exclusively microsporopliylls, 

 which are hypopeltate, hyposporangiate, and bisporangiate. Pilger (1926, 1929), 

 Goebel, and Wettstein (1935) regarded the laminate, hyposporangiate sporo- 

 phyll as the basic form, and its subpeltate form in some Cupressaceae as an 

 advanced condition, while to Dluhosch the basic form was a peltate, centrally 



