UPON PLANT-HOUSES. 99 



20. The ventilation of the building is another point of great 

 weight ; for free air furnishes not only the ixihidum vita to plants, 

 causing the manifold internal movements of vegetation ; but it 

 promotes the act of impregnation, among others by the aid of 

 small insects. The cultivator has moreover the power of adding 

 certain gases to the atmosphere in the house, which may serve, 

 under certain circumstances, to promote vegetation. 



21. Aquatic plants being, with few exceptions, of humble 

 stature, their cultivation belongs properly to low stoves. Some 

 kinds of a taller growth might be suitably provided for in conser- 

 vatory stoves by placing them round fountains or artificial cascades. 

 They will however attain their greatest perfection in stoves espe- 

 cially devoted to their culture, and heated by hot water. 



VII. — Some Account of the Horticulture of Tacna in Peru. 

 By John Reid, Esq. 



(Communicated by Wm. Reid, Esq., Rose Bank.) 



The cultivation of Tacna, as well as that of all other parts of 

 the coast of Peru, is carried on by irrigation. The small stream, 

 dignified by the name of river, has its rise in the neighboui'ing 

 mountains : and the " chacras " or farms extend on either side from 

 where the water leaves the ravine to about two miles below the 

 town, beyond which point the moisture rarely or never reaches. 

 The whole length of the cultivated track is about twelve miles, 

 but its breadth is extremely unequal, caused by inequalities of the 

 surface in some places, and the stony and uncultivable nature of 

 the soil in others ; in no part, however, does it exceed a few 

 hundred yards, and 3000 acres may be taken as a fair approxi- 

 mation to the area of the whole cultivated land. When the 

 Spaniards first took possession of Peru, they parcelled out the 

 ground along the rivers on the coast amongst the Indians, 

 allotting to each division its proportion of water, and fixing the 

 hours at which it was to be taken ; this original regulation is still 

 followed. The valley (all cultivated tracks in Peru are called 

 valleys) is divided into seven districts, to each of which the river 

 belongs exclusively, on one certain day of the week, and is sub- 

 divided among the farms of that part, under the superintendence 



H 2 



