SECRETARY'S REPORT. 55 



with the elements of water, i. c., oxygen and hydrogen, and 

 also in view of the fact that )>lants give oil oxygen largely 

 during active growth, infer that carbonic acid, which is a com- 

 pound of carbon and oxygen, when dissolved in water, is 

 absorbed as carbonic acid by the roots, and constitutes the 

 principal portion of the nutrient material accessible to the 

 plant. Both classes agree in this, that when ultimate decay 

 takes place in the organic matter of the soil, carbonic acid and 

 water are the principal products, with ammonia in some cases. 

 Nature has in her vital domain many niches which the curious 

 chemist is forbidden to enter, and into which the physiologist 

 can only obtain an occasional and partial glance. 



We find on examination, that we are able out of these two 

 opinions to deduce an important practical fact. If the theory 

 first stated be acknowledged, then it follows that the larger 

 the quantity of vegetable matter a soil contains, other things 

 being equal, the greater will be its productive capacity. In the 

 other case, the greater the amount of carbonic acid that the soil 

 possesses, other things being equal, the greater its productive 

 capacity as before, and inasmuch as the cheapest, best and most 

 constant source of carbonic acid is to be found in the gradual 

 decay of vegetable matter, then the more of such material 

 present in the soil, as in the first case, the larger the 

 results attainable by the agriculturist. It has been asserted, it 

 is true, that soil entirely deficient in humus, as this vegetable 

 matter is more commonly called, may be made to produce 

 remunerative crops ; but facts are wanting to sustain the asser- 

 tion, while the experience of the agricultural community goes 

 to contradict it. It is true that the amount of a crop does not 

 bear by any means a direct relation to the amount of vegetable 

 matter in a soil. The condition of that vegetable matter has 

 much to do with it; as for ijistance, peat or muck, which may 

 be entirely made up of vegetable substances, will not afford 

 nourishment to^plants until its crude condition is altered, its 

 acids neutralized, and its surplus water removed. Again, a 

 surplus of vegetable matter, such as sometimes accumulates in 

 long cultivated and highly manured gardens^' will not grow a 

 remunerative crop in consequence of a deficiency of inorganic 

 substances, which, though required in but small quantities, yet 



