342 A CENTURY OF PROGRESS IN THE NATURAL SCIENCES 



CONIPERAE 



As regards the interpretation of the female organs of the conifers there 

 were at the outset four main rivaling theories: (1) the excrescence theory of 

 Sachs-Eichler; (2) the foliolar theory of Delpino and Penzig; (3) the brachy- 

 blast theory of Braun and Celakovsky; and (4) van Tieghem's modification of 

 the last-mentioned theory. Pilger's summary (1926) shows that opinions re- 

 mained divergent. The excrescence theory was supported by Pilger himself and 

 by many others. Penzig (1922) maintained the foliolar theory, while Jeffrey 

 (1917), Eames (1913), Sinnott (1913), Aase (1915), Sahni (1920), Walton 

 (1928), and Zimmermann (1930) professed the brachyblast theory. Wettstein 

 (1911) and Herzfeld (1914) also regarded the female cone as an inflorescence, 

 but the flower was said to consist of a strongly reduced axis axillary to the 

 bract, and of one or more megasporophylls, almost completely used up in the 

 formation of the terminal ovules. Secondary outgrowths from the floral axis, 

 more or less fused reciprocally and with the bract, form the ovuliferous scale. 

 Goebel (1923) agreed closely with Wettstein, but regarded the ovuliferous scale 

 as made up of outgrowths from the megasporophylls. The conifers (including 

 the taxads) were commonly regarded as a monophyletic group, and their female 

 cones were interpreted either as inflorescences or as flowers. However, Lotsy 

 (1911) divided them into the Florales (Podocarpaceae, Araucariaceae, and Cu- 

 pressaceae) and the Inflorescentiales (Taxaceae, Taxodiaceae, and Pinaceae), 

 and Thomson (1909) distinguished one aplosporophyllous group (Podocarpaceae 

 and Araucariaceae) and another diplosporophyllous group (Pinaceae, Taxodia- 

 ceae, and Cupressaceae). If both simple and compound strobili really occurred 

 in the conifers, this would seriously affect the unity of the group. But Eames 

 and Aase showed that the female flowers of the Pinaceae and Araucariaceae are 

 homologous. Eames found that the Araucariaceae, Taxodiaceae, and Podocar- 

 paceae exhibit complete transitions — even within themselves — by fusion and re- 

 duction from forms with distinctly compound strobilar units to other, appar- 

 ently simple forms. Mitra's (1927) discovery of the occurrence of biovulate 

 cone scales in Araucaria suggests that the uniovulate condition is an advanced 

 rather than a primitive feature, and that both types may be derived from a 

 triovulate type. 



According to Dupler (1920), who dealt with the ovuliferous shoot system 

 of Taxus, its primary shoot is a persistent vegetative branch, usually of finite 

 growth, bearing only reproductive (secondary) shoots and functioning for sev- 

 eral successive seasons. The terminal ovule is a truly cauline structure. Its aril 

 had been regarded as a special outgrowth, as a carpel, as an ovuliferous scale, 

 as outer integument, and as the outer fleshy layer of a single integument. Du- 

 pler interpreted it as the fleshy layer of a three-layered seed coat, delayed in 

 appearance. Sahni (1920) proposed the institution of a separate group, the 

 Taxales (including Cephalotaxus), equal in rank to the Coniferae. As to the 

 Torreya ovule, Oliver (1902, 1903) distinguished between the original ovule 

 and a phylogenetically younger intercalated portion by introducing the terms 

 archisperm and hyposperm to designate the respective regions. 



Turning now to the male flowers, one view considered as primitive a more or 

 less radially symmetrical microsporophyll, carrying many sporangia distally. 



