296 Dr Davy's Agricultural Discourse. 



under the influence of oxygen and moisture ; — readily giving 

 up its elements, in the form of carbonic acid, carbonate of 

 ammonia, phosphate of lime, — it is easy to conceive how it 

 may promote vegetable growth, and especially the growth of 

 those plants into the composition of which much azote and 

 phosphate of lime enter, — as in the instance of all the corn- 

 bearing grasses, and all the leguminous plants, and, in brief, 

 all those which are highly nourishing as the food of animals. 

 When I speak of animal matter, I speak of it almost without 

 exception, every part of an animal — (excepting, indeed, fat, 

 a substance which contains no azote or phosphate of lime) — 

 being adapted by its composition to have a fertilizing effect, 

 whether bone or hair, skin or muscle, whether blood or urine. 

 This general fitness of animal matter for the purposes of 

 manure is most deserving of being kept in mind, associated 

 with the fact, that the animal matter does not act, except 

 when undergoing decomposition ; that is, it is not the blood 

 that fertilizes applied to the soil, but the elements of the 

 blood, and so of the urine and other excreta. I beg to call 

 your attention to this, because it appears to me that econo- 

 my is not observed in the West Indies in the use of animal 

 manures. Large quantities of guano are imported at a great 

 cost, and applied to your cane-fields, whilst the bones of all 

 the cattle that are killed for the market, or die of disease, 

 are neglected. I speak of guano and bones thus together, 

 because guano contains a large proportion of the same ingre- 

 dients as bone, viz., phosphate of lime, and so far they are 

 adapted to act the same part. Besides phosphate of lime, 

 guano contains ammoniacal salts. It is a matter, as you are 

 no doubt aware, derived from the excreta of sea-fowl— their 

 urine and dung, partially decomposed. Its nature should be 

 remembered : it should be remembered that the excreta of 

 other animals are hardly less valuable, and, without excep- 

 tion, and as before observed, these are the matters rejected 

 by animals, and noxious to them, which seem by nature spe- 

 cially intended to be the food of plants. Though it little at- 

 tracts common attention, there is not an animal in its wild 

 state that does not promote vegetable life ; the urinary se- 

 cretion of the smallest insect differs but little from that of 



