\8 DR. J. H. GILBERT ON THE 



lime and sulphates of potass, soda, aud magnesia, but no nitro- 

 gen or organic matter (plot 7), the average number of species 

 found has been 42, of which, as without manure, 17 are grasses, 

 4 Leguminosse, and the remainder "miscellaneous." But the 

 produce has contained, on the average, only 55 instead of 62 

 per cent, of its weight of grasses, nearly 26 instead of only 8 

 per cent, (as without manure) of Leguminosae, and only 19 instead 

 of 30 per cent, of " miscellaneous " herbage. 



"With the same mineral manure as on the last plot (7), but 

 with the addition of a large quantity of ammonia- salts, in plot 

 11, the average number of species found has been reduced to 

 21, of which 13 are grasses, 1 only belongs to the order of Legu- 

 minosae, and 7 to other orders. But instead of G2 per cent. 

 by weight of graminaceous herbage, as without manure, or 55 

 per cent., as with the mineral manure alone, we have now, with 

 this mixture of the same mineral manure and a great excess of 

 ammonia-salts, 92*5 per cent, by weight of grasses, only 0-01 per 

 cent, of leguminous herbage, instead of 8 per cent, as without 

 manure, and 26 per cent, with the purely mineral manure ; and 

 we have less than 7£ per cent, of species from other orders, instead 

 of about 30 per cent, as without manure, or 19 as with the purely 

 mineral manure. 



* 



It will be readily understood that, with the great variety of ma- 

 nurial conditions offered by the twenty different experimental plots, 

 there is very great variety in the development and relative predo- 

 minance of the representatives of different Orders and genera in- 

 termediate between the marked extremes above referred to. With 

 reference to the extreme cases cited, the prominent point to ob- 

 serve is, that the grasses dominate to an extraordinary degree where 

 large quantities of ammonia as well as mineral manure were em- 

 ployed, whilst, under these conditions, the leguminous herbage 

 was all but annihilated, and the " miscellaneous " species were very 

 much reduced both in number and in weight per cent, in the 

 produce. On the other hand, the percentage proportion and 

 the actual quantity of the leguminous herbage was enormously 

 increased by a mineral manure containing potass but no am- 

 monia, or nitrogen in any other form, or organic matter of any 



kind. 



Here is obviously a remarkable instance of domination under 



well-defined artificially induced conditions. But the facts are 

 the more remarkable since it is the Graminaceous herbage (which 





