344 GERMINATION — EEQUISITES FOE IT. 



peduncle. In the Balsam (Impatiens noli-me-tangere) the seed-vessel 

 opens with force by a similar process, the five valves curving inwards 

 in a spiral manner, in consequence of the distension of the outer large 

 ceUs. The seeds are discharged before they are dry. In the Mig- 

 nonette (fig. 575, p. 326) the seed-vessel opens early, so as to expose 

 the seeds ; and in Ouphea the placenta bearing the seeds pierces the 

 ovary and floral coverings, and is raised above them. Fleshy fruits, 

 which fall to the ground when ripe, supply by their succulent portion 

 the most suitable nutriment for the young embryo in its earliest 

 stages of growth. 



Wind, water, animals, and man, are instrumental in the dissemina- 

 tion of seeds. Some seeds, as those of Mahogany, Bignonia, Tecoma, 

 Pine, Asclepias, Epilobium, and the Cotton plant, have winged or 

 hairy appendages, by means of which they are wafted to a dis- 

 tance. The same thing occurs in some indehiscent seed-vessels, as 

 the samara of the Sycamore and Ash, and the achsenia'of Dandelion, 

 Thistles, etc. Moisture, as well as dryness, operates in the bursting 

 of seed-vessels. The pod of the Eose of Jericho (Anastatica hiero- 

 chuntina), and the capsule of some Fig-marigolds (Mesembryanthe- 

 mum Tripolium) exhibit the effects of moisture in a remarkable 

 degree. Animals, by feeding on fleshy fruits, the kernels of which 

 resist the action of the juice of the stomach, disseminate seeds ; and 

 man has been the means of transporting seeds from one country to 

 another. In some cases the pericarps ripen their seeds under ground, 

 and are called hyjpocarpogean {b-ao, under, x.ag'^rog, fruit, yia, y^, earth). 

 This is seen in the Ground nut (Arachis hypogsea). Other plants, as 

 Vicia amphicarpos, have both aerial and subterranean fruit. Many 

 seeds are used for food by animals, and a great destruction of them takes 

 place from decay ; but this is compensated for by the vast number pro- 

 duced, so as to secure the continuance of the species. The quantity of 

 seeds produced by many plants is very great. In single capsules of 

 Poppy and Tobacco upwards of 40,000 have been counted. 



Geemination.- — The act by which the embryo of a seed leaves 

 its state of torpidity, and becomes developed as a new plant, is called 

 germination (germinatio, springing). In order that this process may 

 go on, a certain combination of circumstances is necessary. The chief 

 requisites are moisture, air, and a certain temperature. Exclusion 

 from light is also beneficial. In Cotyledonous plants germination 

 may be defined as the act by which the fecundated embryo of a seed 

 leaves the state of torpor in which it has remained for a longer or 

 shorter period, starts into life, as it were, comes out from its envelope, 

 and sustains its existence until such time as the nutritive organs are 

 developed. 



Moisture is necessary in order that the nutritive matters may be 

 taken up in a state of solution, and that certain changes may take 



