REVIEW. 183 



seed into sugar. For this purpose the seed is made to germinate, and this 

 process is stopped (by heating) at that point at which it has been found there 

 is the greatest quantity of saccharine matter in the seed Were germination 

 allowed to proceed further, the saccharine matter would be taken up for the 

 nutrition of the young plants, and its nature completely altered. 



PROPAGATION BY BUDS. 



"Plants are propagated by buds, in four different ways. 1st, By means 

 of the bulbs which grow at the base of the scales in the bulbous root, as in 

 the Snowdrop or Li!ly ; these bulbs are soon detached from the parent bulb, 

 and become independent plants. 2. By means of the bubils which grow 

 upon the stem in the axilla of the leaves, as in the Corral-root (Dentaria 

 bulbiflora), and in the Orange Lilly (Lilium bulbiferum), or in the place of 

 the flowers, as in the Mountain Garlic (Allium Carinatum) ; tbese become 

 detached, and form new plants. 3. By means of the buds or small bulbs 

 which grow at the margins of the leaves in the Bryophyllum, and the bog 

 Orchis (Malaxis paludosa); and 4. By means of the minute buds or eyes 

 found in the tubercles of various plants as the potato (Solanum Tubero- 

 sum). 



" In viparous Alpine Bistart (Polygonum Viviparum") the pistil of the 

 lowermost flowers generally become a bulb (bud) which begins to grow and 

 throw out leaves before it falls off, and being detached, strikes root and 

 forms a new plant. The seeds in this plant are seldom ripened. Sheep's 

 Fescue Grass (Festuca ovina) frequently produces in place ol flowers, buds, 

 as fall off as bulbs, and vegetate ; this is also the case with Alpine Meadow- 

 grass (Poa alpina) and Sand Garlic (Allium arenarium). Plants which form 

 buds or bulbs which they throw off, and which then vegetate independently, 

 are called viviparous. 



" All these resemble seeds in this, that when detached from the parent 

 and placed in the earth, they produce new plants. They differ from seeds 

 in not being formed by flowers ; in not being able to preserve their vitality 

 for such a length of time ; in not having distinct parts such as radicule, 

 gemmule, and cotyledons, being merely extensions of the substance of the 

 parent ; and in always producing the same variety. Hence one advantage of 

 propagating the Potato by buds ; we have found a variety well adapted for 

 use as an article of food, and we can ensure its reproduction. If grown 

 from a seed, a very different variety might be produced, which would not 

 have the same nutricious properties. In fact, plants arising from buds, are 

 regarded as a continuation of the same individual— hence they in time be- 

 come exhausted and deteriorated. 



PROPAGATION BY SLIPS AND LAYERS. 



" Propagation by layers consists in surrounding a young branch with moist 

 earth, in which case it throws out roots, and very soon becomes an inde- 

 pendent plant. It is customary to make a small incision at the part placed 

 in the earth, or to pass a ligature round it. This intercepts the descending 

 sap, which, by being accumulated, excites the latent buds, and these being 

 developed in the earth, become roots. 



" Sometimes the branch is bent downwards and fastened in the earth, as 

 in the Vine, which is always propagated in this way ; and many plants pro- 

 pagate themselves naturally in this way, the stems or branches lying on the 

 earth, and taking root where they come immediately in contact with it, as the 

 Currant bush and Laurel. At other times the branches are surrounded with 

 earth in its natural position, and detached when it has taken root. 



" Propagation by Slips much resembles the preceding mode. The only 

 difference is, that the branch or slip is detached from the parent before being 

 made to put out roots. The slips or cuttings of most trees that have a light 

 white wood, as the Willow, the Ash, or the Poplar, easily take root when 

 placed in the earth ; and indeed the Willow ia reproduced chiefly in this 



