Feb, 3, 1870] 
NATURE 355 
mental plot, and the appearance of the crop will tell him 
what is deficient in the soil. And in making his experi- 
ments, he is not restricted to any special kinds of plants, 
for the method may be applied to the sugar cane, the 
sorgho, and other natives of the tropics, to maize, 
beetroot, the Jerusalem artichoke, the potato, colza, and 
other varieties of cabbage, and to flax and hemp. Whether 
saccharine, or oleaginous, or fibrous, or starchy, the plants 
may be developed to the utmost limit of their productive- 
ness by proper treatment. 
The complete fertiliser, or exgrazs complet, as Prof. 
Ville calls it, varies slightly in composition according to 
the nature of the crop required. For wheat it is com- 
posed of acid calcium phosphate (superphosphate of 
lime), potassium nitrate (nitre), ammonium sulphate, and 
calcium sulphate (gypsum). These materials require to be 
skilfully mixed, so as to retain all their beneficial properties 
when spread upon the land. The “engrais complet” is to 
be regarded as the typical fertiliser—the standard by which 
to judge of the value and the lastingness, so to speak, of 
any chemical manure. A field properly treated with this 
will return three or four crops of wheat in immediate 
succession, without further manuring in the meantime. 
For the proper carrying on of the experiments, it would 
be necessary to have— 
1. The complete compost. 
2. Compost without potassium salts. 
3: x without phosphates. 
4. _ without nitrogenised matter. 
These are to be applied to the experimental plots of 
land. If then, number 2, or 3, or 4 produces the same 
effect as number 1, it is evident that the substances repre- 
sented by those numbers exist already in the soil, that the 
vegetation has profited by them, and that there is no need 
to apply them to the land. If, on the contrary, the com- 
post in which any one of the four substances is wanting 
produces a deficient crop, there is a certain proof that 
this particular element of productiveness is deficient in 
the land. 
Here, then, is a method of analysing the soil of fields 
and gardens which even an intelligent labourer might 
practise. He could hardly continue the practice without 
learning, better than from books, the true principles of 
agricultural science. He could determine step by step 
the loss of any one or more of the fertilising elements, and 
consequently ascertain which was required to restore the 
fecundity of the soil. 
In support of this argument, Prof. Ville brings forward 
some remarkable results obtained on his experimental 
farm at Vincennes, giving tables showing the cost of 
cultivation and the yield of each experimental plot. He 
also places before his readers a series of figures in which 
the results obtained with wheat are displayed in a most 
forcible manner. The two examples here given indicate 
the limits of his experimental system. The sheaves are 
represented on the same scale, so that the results of good 
feeding and starvation may be readily compared. The 
intervening figures may be imagined. 
If the experiment be made with peas, there is a marked 
difference in the result: the nitrogenised matter which 
tells in the culture of wheat has little or no effect on 
leguminous plants ; the reason being that wheat takes up 
from the soil most of the nitrogen it requires, and that 
leguminous plants derive it mainly from the air. To 
produce a good crop of the latter we must employ a 
manure containing an excess of potassium salts, and for 
turnips we require an excess of calcium phosphate. 
These are important facts, for they show that besides 
variation and rotation of crops, there can be also rotation 
of manures. Take any average field, and apply to it the 
materials which act on the required crop, and so pass 
from one to the other until the land shall have received 
all the materials which make up the complete compost. 
This, briefly sketched, and with omission of certain 
practical details, is Prof. Ville’s system for the improve- 
ment of agriculture in France. The five million small 
proprietors, who own each from 3 to 14 hectares, have 
herein a simple and efficacious method, by which their 
profits may be largely increased, and their own con- 
dition materially ameliorated. To quote the Professor’s 
words, “The tiller of the soil is always in presence of a 
Power superior to himself. Seasons, temperature, rain, 
and sunshine, which enter so largely into the success of 
his labours, are above his influence. He learns that skill, 
foresight and economy are required of him; he knows 
also that when he has done all that depends on himself 
he must be resigned and wait. By temperament, as much 
as by condition, he becomes above all the friend of order, 
and, in case of need, its firmest support.” 
OUR BOOK SHELF 
Landwirthschaftliche Zoologie. Won Dr. C. G. Giebel. 
8vo. pp. 827, with 510 woodcuts. Glogau, 1869. Carl 
Fleming. (London: Williams and Norgate.) 
ALTHOUGH the study of economic zoology ought to be 
of some importance in this country, we can point to very 
few English publications relating to it,—Curtis’s “ Farm 
Insects,” and the translation of Kollar’s “Garden Insects,” 
by Westwood and Loudon, being almost the only special 
works on the subject that we can call to mind, and these 
are now of old date. This may perhaps be due to the 
fact that the advantage of attempts at the practical ap- 
plication of zoological and, especially, of entomological 
knowledge, is very frequently doubtful, but it is certain 
that in many cases an acquaintance with the natural 
history of animals must be most valuable to the farmer or 
gardener, by enabling him to distinguish beneficial from 
injurious creatures ; it is therefore much to be regretted 
that we possess no good treatise which would place the 
necessary knowledge within reach of our English agri- 
culturists. 
There is another point of view in which the study of 
economic zoology is of great importance. From the 
very nature of their relations to man and the organisms 
which he has taken under his care, useful and injurious 
animals acquire a remarkable prominence, and thus 
the phenomena of their existence are brought near to 
us and, as it were, magnified in such a manner 
as to render their investigation comparatively easy. 
Accordingly, there can hardly be any better means of 
acquiring a practical general knowledge of natural his- 
tory and, especially, of the intimate and intricate relations 
of organised beings, than the study of the enemies and 
benefactors of the farmer and gardener. 
Dr. Giebel seems to have taken this view of the matter, 
and his “Agricultural Zoology” is really a complete 
natural history of terrestrial animals, the illustrative 
examples being drawn from domestic animals, or from 
species which exert a more or less direct influence upon 
the results of agricultural operations. Of all these, the 
natural history is given by Dr, Giebel in considerable 
