1917] 



H U TCHINSON—KE TELEERIA 



129 



terminal 



is about one-sixth of that of the tube. At the base the tube is in 

 the form of a hollow cylinder (fig. 19) above; the inner surfaces 

 become rectangular, then star-shaped in outline (figs. 16, 17); 

 finally, the 4 cotyledonary tips become separate (fig. 16). 



Occasional seedlings of Abies and Finns have been described 

 (7> 8, 9, 10) having limited cotyledonary tubes, but no such pro- 

 nounced structure as occurs in Keteleeria has been recorded. 

 Although the material did not show the earlier stages,' it seems 

 evident that the situation here is similar to that existing in angio- 

 sperms (3, 4); that cotyledons, whether several as in Coniferales, 

 two as in dicotyledons, or one as in monocotyledons, are all similar 

 in origin; that the cotyledonary growth is, primarily, that which 

 results from a meristematic ring about the leaf bud, the number 

 of cotyledons being dependent upon the number of the loci of 

 increased growth. In Keteleeria the major part of cotyledonary 



elongation is uniform throughout the entire ring of the growth 

 region. 



With the exception of the central axis, the regions of the 

 primary root are similar to those of other conifers; in Keteleeria 

 this region is continuous throughout, while in other conifers 

 described it is broken by the meristematic region. It is evident 

 that such a modification in structure is due to the nature of the 

 meristem. Since the meristem of certain conifers, including 

 Keteleeria, is being described in another paper, details may be 

 omitted here. 



The differentiation of tissues as they occur in the embryo of 

 the mature seed is advanced beyond the stage usual for conifers 

 (7, 8, 9, 10). In the primary root the first cells to become differ- 

 entiated are those which later become mucilage tubes (shown in 

 black, figs. 15-27). The cells cease to divide and become vacuolate 

 (fig. 11); the nucleus disintegrates; the cells are greatly elongated 

 by division and growth of the surrounding cells and become muci- 

 laginous in content. Similar cells, except that they are much 

 shorter, are formed in the coleorhiza. The cells of the cortex 

 become filled with food materials, generally in the form of starch 

 (fig. 12). The cells forming a hollow meristematic cylinder about 



