20 



EXCESSIVE DEVELOPEMENT OF HOOTS. 



thousand ramifying rootlets, bespangled with 

 minute crystal-like damp drops, and extending 

 over a space of five feet in width. It was dif- 

 ficult to trace the brittle roots that had pene- 

 trated the sawdust, but he measured some 

 upwards of seven feet below the surface of the 

 brickwork on which the plants were growing. 

 It is this peculiarity which renders it so diflS.- 

 cult to keep draias or wells in working order 

 where roots have access. A well sis feet wide 

 has been known to be filled with roots by a 

 common Laurel bush. Turnips and Mangel 

 "Wurzel, as well as mere weeds, have great 

 power ia this way. Patrick NeHl mentions an 

 instance of a plant of Ragwort (Senecio 

 Jaoobsea) which had insiauated the point of 

 its roots into a drain, and had then extended 

 them so much as to fill the drain completely 

 for about twenty feet. And thus it is seen 

 that it is by the point that roots extend, with 

 an indefinite power of branching, and that the 

 finest thread once introduced into a drain-pipe 

 will rapidly become the origin of most exten- 

 sive mischief, provided the plant is perennial. 

 A still more remarkable case is mentioned in 

 the Gardeners^ Chronicle for 184;9, of a line of 

 pot-pipes from forty to fifty feet long, socketed 

 and cemented, and thought to be perfectly 

 closed, having become so choked by roots as to 

 be unserviceable in fifteen years. In the side 

 of one of the pipes there had been one mere 

 chink ; and through that chink some tree had 

 insinuated the point of some root. .Once in- 

 serted the point lengthened and divided, and 

 lengthened and divided over and over again, 

 till at last the drain-pipe was filled by an en- 

 tangled mass of fibres which had pressed so 

 firmly against each other as to form in some 

 places a tolerably perfect mould of the cavity. 

 Roots lengthen, as already stated, not by 

 extension, but by pei-petaal additions of very 

 soft ceUnlar matter to their points. That mat- 

 ter is in fact in the beginning mere mucilage 

 capable of organisation. A small portion of this 

 mucilage finds itself in contact with a minute 



