358 HOt'MEISTER, ON 



account of the less active development of the corresponding 

 region of the bark-forming cambium, and it becomes deeper 

 still by the regular tearing away of the tissue of the bark 

 from the sides, that tissue not being stretched transversely. 



The roots of the previous year are pushed for some dis- 

 tance outwards and downwards with the bark through 

 which they have penetrated. Like the latter they assume 

 a deep brown colour and die. 



The new roots destined for the support of the plant 

 during the current period of vegetation originate on the 

 convex edge of the lower, half-moon-shaped portion of the 

 mass of wood, by the multiplication of some of the cambial 

 cells adjoining the wood. The nature of their cell-multipli- 

 cation corresponds in almost every respect with the account, 

 given above of the first root. The only difference is that 

 during the passage through the bark the transient cellular 

 layers of the root-caps are inordinately developed, and the 

 permanent cortical layer of the root, on the other hand, very 

 slightly so. 



The first root of the second year is formed close under 

 the place of origin of the first root of the germ-plant, at the 

 spot where the development of the cambium has torn off 

 the vascular bundle of the root about to be cast off — i. e., at 

 the place of attachment of the latter root. The second root 

 originates underneath the place of insertion of the second 

 root of the previous year, the third under that of the third 

 root of the previous year, and so forth. In their direction 

 also the new roots aoree entirely with the older ones. The 

 two first originate opposite to one another, trending away 

 from the lateral surfaces of the lower growth of wood, and 

 bent in different directions inter se. They break forth op- 

 posite to one another in a perpendicular direction underneath 

 the terminal bud, on both sides of the furrow of the stem. 

 The third and followino- roots bend more and more side- 

 ways. The two last pairs of roots of one period of vegeta- 

 tion traverse the bark almost parallel to the furrow of the 

 stem. All the roots as thev qtow through the bark describe 

 a flattened are concave to the indentation of the stem. A 

 longitudinal section taken through that indentation lays 

 bare within each half of the stem onlv the rudiments and 



