254 (ilJMI'SKS INTO PLAMT-I.IFE 



and the greater part of the " roots " of radishes 

 and turnips is due to it. In other instances it is 

 a mere collar forming a sHghtly thickened surface 

 between the base of the cotyledon and the radicle. 

 The tigclluDi is in realit}' a centre of growth, as 

 may easil)' be shown b)' cutting off an inch of the 

 upper part of a well-grown carrot and placing the 

 slice in a saucer of water ; before long a crown of 

 young leaves will spring up and will continue to 

 grow and flourish as long as the plant food 

 contained in the slice is sufficient to maintain the 

 leafage. In botanical language we have thus been 

 growing carrot leaves from this tigellnni. 



The embryo varies very much in the relative 

 position of its parts. Thus the embryo of the 

 reed-mace is straight in the tigclhim of the em- 

 bedding albumen. In contrast to this is the curved 

 embryo of the deadly nightshade and the spiral 

 embryo of the hop. 



The seeds of the orange often contain two em- 

 bryos, which is rather a rare occurrence in the vege- 

 table world. Before we can trace the future of these 

 parts we must attain a clear idea of the change 

 the seed undergoes when it germinates. In the 



