THE LIFE-HISTOEY OF PLANTS. 



21 



of tke practitioner in the laboratory, before tbey can 

 be made safely available for the guidance of the 

 practitioner in the garden. For full information as 

 to the existing state of structural botany, or of those 

 tlepartmenta of chemistry and physios 

 ■which are inseparably bound up with 

 the physiology of plants, the reader 

 must consult the standard text-books. 

 All that we can do here is to call atten- 

 tion to the leading phenomena of plant- 

 life, as observed under conditions in 

 which they are brought under the 

 notice of the cultivator in the course of 

 his ordinary routine. 



Gro'wrtli. — As we have to trace the 

 record of plant-life from day to day in 

 due sequence from its beginning to its 

 end, it mat- 

 ters little at 

 what part of 

 the cycle we 

 begin; but as 

 growth is the 

 most strik- 

 ing pheno- 

 menon ob- 

 servable at 

 the time 

 when these 

 pages come 

 before the 

 reader, it 

 may be ap- 

 propriate to 

 begin our re- 

 marks with 

 that subject. 

 The pro- 

 priety of this 

 will strike some 

 so forcibly that 

 they will natu- 

 rally think no 

 other course than 

 that of "begin- 

 ning at the begin- 

 ning " would be 

 correct. And 

 this is no doubt 

 the case ; but, un- 

 fortunately, we do not know where to fix the 

 starting-point. Neither the seed nor the bud 

 can be strictly considered as beginnings— seeing 

 that they are merely remanets from last season's 

 growth. 



Fig. 2. — Germinating Seed 

 of Caujia, sHowing the 

 black seed-husk, audthe 

 seedling plajit protrud- 

 ing its two growing 

 points, one upwards to 

 form the stem, the other 

 downwards to form the 

 root (shghtly enlarged). 



rig. 3. — End of Hoise-chestnut sur- 

 rounded hy scales, the outer of 

 ■which are becoming shed by the 

 growth of the grotring point 

 within. 



Fig. 4. — Sectiou showing 

 the Seedling Plant of 

 Canna, sitcrounded by 

 the food-store in the 

 perispenn (enlarged). 



Practically, however, we may take them as start- 

 ing-points, in which the activity of the plant chiefly' 

 shows itself, after the rest and relative cessation of 

 work of the winter season. 



Reserve Organs.— Sharply-drawn 



definitions are not apphoable, except to 

 a very limited extent, in any branch of 

 natural history or physics. One thing 

 is always wholly or partially inseparable 

 from some other thing. The several 

 parts act and react upon one another, 

 so that anything like an absolute line 

 of demarcation which shall hold good 

 in all cases, at all times, and under all 

 conditions, must not be looked for. 

 Hence, when we say that the seeds and 

 buds, and their modifications, with 

 ■which we are 

 now princi- 

 pally con- 

 cerned, are 

 " reserve or- 

 gans," it 

 must not be 

 inferred 

 either that 

 they have no 

 other oiEce, 

 or that no 

 other parts 

 of the plant 

 can fulfil the 

 same duty. 



Both seed- 

 and bud (we 

 are speaking 

 especially 

 of leaf-buds) 

 contain a 

 "growing point" 

 in their interior, 

 but the growing 

 point of a bud, or 

 of a bulb (which 

 is only a form of 

 a bud), remains 

 attached to the 

 shoot from ■which 

 it originated, and 

 grows principally 

 in one direction (Figs. 1,3); the growing point of a 

 seed is detached entirely from the seed, and grows in 

 more than one direction (Fig. 2). The gxo-wing point 

 of a seed is, in fact, the genn or embryo plant which, 

 on its escape from the seed, becomes the seedling. 



Fig. 5.— Portion of the Perisperm of the Seed 

 of Wheat, highly magnified, to show the 

 food-store in the shape of grains of 

 starch. 



Fig. 6.— Section of Seed of Date, showing the 

 hard, homy perisperm from wbich the 

 minute embryo (shown in the centre 

 and close to the upper edge) derives its 

 nourishment. 



