ON GKONVTH AXD EXTENSION IN THE VEGETABLli KlNUDOiM. 29 



lengthening of the cells cannot alone have produced the growth 

 of the fibre, for the cells in the added portions must have 

 been formed before they lengthened. Now as the lengthening 

 proceeded from the part immediately above the root-point, or 

 from the origin of the root-point itself (for the limits of the 

 increase cannot be determined very precisely), consequently the 

 new cells must have been there formed. And in fact it is tliere 

 that we find a number of small, irregularly crowded, unarranged 

 cells, which witliout doubt lengthen after tliey are formed, and 

 continually force onwards the root-point. The growth of the 

 fibrous roots lakes place, tlierefore, much in the same manner as 

 that of nails and hairs in animals ; these parts receive nourisli- 

 ment at the base only, and the points are always pushed forward. 

 If the points are cut off the root-fibres, they cease to grow ; so it 

 is also if the points are crushed or otherwise injured. They then, 

 rot very easily, and it is therefore advantageous to cut the ends 

 of roots in transplanting when there is any reason to believe that 

 they have been injured. 



Before we proceed further I would add a few remarks. The 

 root-point is a very curious portion of the plant. It is distin- 

 guished externally by its globular shape and lighter colour ; in- 

 ternally, as we have already seen, by the circumstance that neither 

 vessels nor the accompanying extended cellular tissue penetrate 

 into it.* This last character has been hitherto overlooked. 

 The lower portion of the root-point consists of rather large 

 angular cells, containing globular grains of starch collected into 

 a mass, and turning blue with iodine. In those root-points of 

 the hyacinth which I have examined, this has always been tlie 

 case ; but in the root-points of other plants the granules in the 

 cells have turned brown with iodine, as occurs also in the upper 

 cells in the hyacinth. The cells of the root-points are round or 

 angular, larger or smaller, and even extended transversely ; and 

 there are always' to be found on the outside some cells which 

 scale off, and in their place others are produced, which in their 

 turn scale off, thus constituting the well-known scales of the 

 root-points. Here these outer cells are long and narrow ; in 

 many other plants they are shorter and broader. Many philo- 

 sophers have believed that the root-points served to suck up the 

 nutritive juices from the soil, and De Candolle on that account 

 called them sponyioles : but the very accurate observations of 

 Ohlert (Linnsea, 1837, p. 609) prove that this is not at all the 

 case, for plants whose root-points hang free in the air continue 

 to grow, even when these points are cut off and closed with seal- 



* The vessels (spiral or porous vessels) are almost always accompanied 

 >iy long, narrow cells —the extended cellular tissue. 



