GYMNOSPERMS: WHITE PINE. 



309 



bears lateral leaves, and in some cases all gradations are present between 

 these lateral leaves on the axis and their consolidation into an ovuliferous 

 scale. In the normal condition of the ovuliferous scale the axis has disap- 

 peared and the shoot is represented only by the consolidated leaves, which 

 would represent then the 

 macrosporophylls (or carpels) 

 each bearing one macrospo- 

 rangium (ovule). 



One of the most interesting 

 and plausible views is that 

 of Celakovsky. He believes 

 that the axial shoot is reduced 

 to two ovules, that the ovules 



Fig. 362. 



Pine seed, section of. sc, 

 seed coat ; n, remains of nu- 

 cellus ; end, endosperm 

 (= female gametophyte); 

 emb, embryo = young spo- 

 rophyte. Seed coat and 

 nucellus= remains of old 

 sporophyte. 



Fig. 363- 

 Embryo of white 

 pine removed from 

 seed, showing 

 several cotyle- 

 dons. 



Fig. 364- 



Pine seedling just 

 emerging from the 



have two integuments, but the outer integument of each has become pro- 

 liferated into scales which are consolidated. In this proliferation of the 

 outer integument it is thrown off from the ovule so that it only remajns 

 attached to one side and the larger part of the ovule is thus left with only 

 one integument. This view is supported by the fact that in gingko, for 

 example (another gymnosperm), the outer integument (the "collar") 

 sometimes proliferates into a leaf. Ceiakovsky's view is, therefore, not 

 very different from the second one mentioned above. 



