EMBRYOGENESIS IN FLOWERING PLANTS 251 



closely involved in cell division and in the positions in which cell walls 

 are laid down, the morphological facts of embryology will gain in 

 value and this branch of botanical science will move forward into a 

 new and dynamic phase. 



In the view of Maheshwari (1950), a knowledge of angiosperm 

 embryology throws little light on the ancestry of the group, though it 

 does indicate their probable monophyletic origin. He considers that 

 there are no fundamental differences between dicotyledons and mono- 

 cotyledons, features of a transitional or intermediate character being 

 present in both groups. Angiosperm embryology provides little that 

 enables us to relate this group to other subdivisions of the Plant 

 Kingdom, but the primitive families of the Winteraceae, Degeneriaceae 

 and Trochodendraceae, of which the general morphology and anatomy 

 have been studied by Bailey and his colleagues, may yield data of some 

 interest in this connection {see Chapter XIV). 



THE SEED AND SEEDLING 



In flowering plants, as in gymnosperms, the embryogenic process 

 culminates in the formation of the mature seed awaiting dispersal. 

 The form of the embryo within the mature seed, the construction of the 

 seed, the conditions under which it germinates, the estabhshment of the 

 seedling, and its morphology and anatomy, constitute the logical 

 extension of the work presented here. In this connection the reader 

 may be referred to Netolitzky (1926) and to recent papers by Corner 

 (1951) and Singh (1952). Factors determining the delayed germination 

 in economic seeds have been considered by Rose (1915). Longevity of 

 seeds under natural conditions and in storage has been considered in 

 a classical work by Ewart (1908); more recently it has been reviewed 

 by Crocker (1938) and considered comprehensively by Crocker and 

 Barton (1953). The reader is referred to the latter authors for recent 

 records and bibhographical details. 



