On the Structure of Roots. 489 



Roots of this kind show very clearly that the elongation of 

 roots takes place by increase at the point only. This is seen by 

 noticing the relative dimensions of the cells in the different parts, 

 but it may be proved still more evidently by marking the roots, 

 when of some length, at equal distances, with touches of Indian 

 ink. When we watch the farther growth of a root thus marked, 

 we see that the spots on the upper part of the root do not become 

 removed to a greater distance from each other, but new structure 

 is added on below the marked parts. The same important law 

 of growth is illustrated by the natural marks made by branches 

 arising from the roots, which remain permanently at their original 

 distance apart, as may be clearly seen in the transverse streaks 

 on the surface of the root of a carrot. 



In the seeds of the grasses, of which we may select barley as 

 an example, the radicle or rudimentary root is a minute, blunt, 

 conical projection at the base of the embryo, which itself is 

 situated at one side of the bottom of the farinaceous mass of 

 endosperm which forms the great bulk of the seed. A germi- 

 nated seed of barley exhibits the valves of the husk open more or 

 less at each end, the leaves emerging in front, and several delicate 

 thread-like roots at the other. Removing the husk, the leaves 

 are found to arise from a thickened place or knot previously con- 

 tained within the husk, the part of the stem below this knot 

 ending in a blunt process, which is the undeveloped radicle ; the 

 filamentous roots have been pushed out from the base of the 

 cotyledon, between the point of the radicle and the knot. The 

 root filaments present characters similar to those of tlie onion, 

 but differ in the presence of abundance of branches and Jibrils. 

 From this peculiarity, such roots possess greater vitality ; for 

 if a root of an onion is injured at its extremity, its growth is 

 entirely arrested ; while the rootlet of a grass injured at the 

 point may freely develop lateral branches, like the roots of 

 Dicotyledons. . 



The general observations upon roots contained in the present 

 paper, have been prepared as introductory to a detailed account 

 of the development of agricultural roots. The observations upon 

 the turnip are tolerably complete, and will be shortly submitted 

 to the Society. 



XXI. — Horse Labour in France. By F. R. DE LA Trehonnais. 



The use of horses for agricultural labour is rather limited in 

 France. In most of the midland and southern districts oxen 

 and even cows are used by the peasants to draw their ploughs, 

 and perform other operations of husbandry. Indeed, such a 

 VOL. XIX. 2 K 



