CHAPTER X. 



Leguminous Plants. 



THE Legumes, or Pulse, are, perhaps, next to the 

 Cerealia and the Potato, the most important of escu- 

 lent vegetables. They are numerous, most univer- 

 sally diffused, and many which are not applicable for 

 human food can still be advantageously used as nou- 

 rishment for domestic animals. 



The whole of the edible legumes, with the excep- 

 tion of some of the species which grow on trees, have 

 their flowers papilionaceous, or resembling butterflies 

 in shape. The seeds are contained in an oblong le- 

 gumen, or pod, consisting of two valves, on the upper 

 suture of which they are placed alternately on each 

 side. These seeds, in germinating, have no power of 

 pushing forth more than one stem, as in the case, of 

 the cerealia, so that the pea does not tiller, but the 

 buds on the stem produce fertile branches. 



Carbonic acid gas is always generated when plants, 

 particularly leguminous plants, are in the greatest 

 vigour of vegetation. The quantity of this gas which 

 is then given out, and more especially during the 

 period of flowering, is very considerable, and being 

 heavier than atmospheric air, it is carried along the 

 surface of the earth into pits and cavities, in the 

 same manner as a flood of water would be carried, 

 only that its effects are the sole indications of its 

 presence. 



It is said that miners, in fertile districts where le- 

 gumes are extensively cultivated, are but too well 



