640 BRITISH ASSOCIATION FOR ADVANCEMENT OF SCIENCE. 
tract, whether the electric current had its origin in the animal body, or from 
a source external to that body. Galvani erred in too exclusive a reference 
of the electric force producing the contraction to the brain of the animal : 
Yolta in excluding the origin of the electric force from the animal body alto- 
gether. The determination of “the true” and “the constant” in these re- 
condite phenomena, has been mainly helped on by the persevering and inge- 
nious experimental researches of Mateucci and Du Bois Reymond. The 
latter has shown that any point of the surface of a muscle is positive in re- 
lation to any point of the divided or transverse section of the same muscle ; 
and that any point of the surface of a muscle is positive in relation to any 
point of the divided or transverse section of the same nerve. Mr. Baxter, 
in still more recent researches, has deduced important conclusions on the 
origin of the muscular and nerve currents, as being due to the polarized 
condition of the nerve or muscular fibre, and the relation of that condition 
to changes which occur during nutrition. From the present state of neuro- 
electricity, it may be concluded that nerve force is not identical with electric 
force, but that it may be another mode of motion of the same common force : 
it is certainly a polar force, and perhaps the highest form of polar force. 
Progress oe the Science of Agriculture. 
Agriculture has of late years made unusual progress in this country, and 
much of that progress is due to the application of scientific principles; 
chiefly of those supplied by Chemistry ; in a less degree of Zoology and 
Physiology. Geology now teaches the precise nature and relations of soils : 
a knowleege of great practical importance in guiding the drainer of land, in 
the modifications of his general rules of practice. Palaeontology has brought 
to light unexpected sources of valuable manures, in phosphatic relics of 
ancient animal life, accumulated in astounding masses in certain localities 
of England, as, for instance, in the red-crag of Suffolk, and the green-sands 
of Cambridge. But quantities of azotic, ammoniacal, and phosphatic 
matters are still suffered to run to waste ; and, as if to bring the wasteful- 
ness more home to the conviction, those products, so valuable when rightly 
administered, become a source of annoyance, unremunerative outlay, and 
disease, when, as at present in most towns, imperfectly and irrationally dis- 
posed of. 
In the operations of Nature, there is generally a succession of processes 
co-ordinated for a given result : a peach is not directly developed as such 
from its elements ; the seed would, a priori, give no idea of the tree, nor 
the tree of the flower, nor the fertilized germ of that flower of the pulpy 
fruit in which the seed is buried. It is evidently characteristic of the Crea- 
ative Wisdom, this far-seeing and prevision of an ultimate result, through 
the successive operations of a co-ordinate series of seemingly very different 
conditions. The further a man discerns, in a series of conditions, their co- 
ordination to produce a given result, the nearer does his wisdom approach — 
though the distance be still immeasurable — to the Divine wisdom. One 
philanthropist builds a fever hospital, another drains a town. One crime- 
preventor trains the boy, another hangs the man. One statesman would 
raise money by augmenting a duty, or by a direct tax, and finds the revenue 
not increased in the expected ratio. Another diminishes a tax, or abolishes 
a duty, and through foreseen consequences the revenue is improved. Water 
is the cheapest and most efficient transporter of excreta : but it should be 
remembered that the application of the water-supply as a transporting 
power is to be limited to all that comes from the interior of the abodes ; 
this alone can be practically and successfully applied to agriculture. What- 
ever flows from the outside of houses, together with the general rainfall of 
the town area, should go to the nearest river by channels wholly distinct 
