March 22, 1883} 
to draw any certain conclusion regarding the relation of 
non-pathogenous to pathogenous bacteria. Clinical ex- 
perience would indicate that the activity of the infective 
virus may vary within certain limits. And we must appa- 
rently admit that the infective bacteria have not always 
possessed their noxious qualities, but have acquired them 
somehow inthe course of ages. But this is not enough to 
convince us that harmless bacteria can acquire infective 
properties rapidly. . . . We may therefore provisionally 
conclude that the transformation of innocuous into 
noxious bacteria can occur but rarely, and under special 
conditions.” 
Recent work both in this country and on the 
Continent seems to go against the mutability theory, 
and in all probability it will soon be made clear that 
Buchner’s experiments are capable of another interpreta- 
tion from that hitherto adopted. 
Enough has been said to indicate that the English 
edition of Ziegler’s Pathology will not only prove of 
immense help to the student, but that it will also be 
invaluable to the practitioner. It is to be hoped that 
the second part, on Special Pathological Anatomy, will 
soon appear, and that it will equally commend itself to 
English readers. 
The numerous woodcuts with which the work is illus- 
trated are beautifully distinct, the type and paper are 
everything that could be desired, and so successful has 
the editor been that there is no evidence of the greater 
part of the work being a translation. 
ENSILAGE 
Ensilage in America. By James E. Thorold Rogers, 
M.P. (London: W. Swan Sonnenschein and Co., 
1883.) 
ROFESSOR ROGERS has contributed a most in- 
teresting little book on Ensilage in America. He 
has no doubt been serviceable to his country in drawing 
public attention to a subject of importance ; but like most 
persons who focus their eyes upon a single point, he has 
lost the due proportion in which it stands to its back- 
ground, foreground, and surroundings. Perhaps this may 
be forgiven as a common fault, or it may be the secret of 
strength, in all propagandists. Be this as it may, it is a 
marked feature in the volume before us. Ensilage is to 
be the temporal salvation of the farmer. The Professor 
appears to have been carried away on the full tide of 
American enthusiasm, buoyed up bya certain youthful 
airiness scarcely consistent with the gravity of an Oxford 
Don. He has forgotten the salt, and those who read his 
book (and we trust they may be numbered by thousands) 
must add it for themselves. 
Ensilage is the preservation of green fodder in its 
natural succulent condition in pits or Sz/os. These pits 
must be airtight and watertight, and the fodder must be 
so well trampled into them and weighted on the top as to 
arrest fermentation. The theory of the process is that, in 
the case of fodder so treated, heat is generated and 
fermentation commences. The small amount of oxygen 
held in the interstitial air is speedily absorbed, and its 
place taken by carbonic acid gas. Just as a lighted candle 
extinguishes itself in a bath of choke-damp of its own 
making when burnt in a closed vessel: so the fermenta- 
NATURE 
479 
tion and its accompanying heat are arrested in the mass 
of closely packed fodder which is in fact immersed in a 
bath of carbonic acid, and thus securely protected from 
ordinary atmospheric action. Well preserved ensilage 
comes out of the pit almost as green and fresh as when it 
was first put into it, and has acquired a pleasant vinous 
smell and slightly acid flavour, which has given it its 
name of sourhay in Germany, Austria, and Hungary. 
The process is at once simple and effective, but is no 
doubt expensive when carried out upon the scale which a 
successful experiment demands. Thus the larger the pit 
the more assured the success, as all the conditions are 
more perfectly attained. At p. 22 we read: “ M. Have- 
meyers silos were four—two fifty-nine feet long and 
fourteen feet wide ; and two thirty-five feet long and 
twelve feet wide, each pair being twenty-five feet deep. 
They are under the same roof as the feeding barn, where 
there is standing-room for ninety-eight cows.’’ The pits 
are bricked and cemented, or built with concrete walls, 
and they may be carried up higher than the level of the 
ground, or may be built entirely from the surface. When 
the ground is naturally dry and of a clayey or close 
texture the silo need not be lined. It is recommended 
that a drain should if possible be carried from the bottom 
of the silo to take off superfluous water. Simple as these 
directions undoubtedly are, they point to a heavy initial 
expenditure, only to be recommended after very mature 
consideration. On the other hand silos of smaller size, 
as, for example, 22’ X 9’ X 15’ deep and other dimensions, 
are also mentioned. Still the fact remains that in small 
silos there is more waste and greater uncertainty. Also 
that for practical purposes a small silo would be of little 
value. The process of storing the fodder is very easy to 
understand. It is, in the case of green maize, cut up 
with a powerful chaff-cutter, trampled into the pit by men 
or horses, and when the space is filled it is covered with 
boards and weighted down with boxes of stone or earth 
to a pressure of about 100 lbs. per square foot. The 
fodder settles down under pressure, and is found after 
several months to be perfectly palatable and fresh. 
Such is the process which Prof. Rogers now lays before 
the British public with the strongest possible recom- 
mendations. Not only so, but with threatenings or at 
least warnings also, for we are told that “if the New 
Englanders and New Yorkers succeed in extending their 
ensilage system, they will strive to find a foreign market 
for their increased produce.’ This process, it is urged, 
is entirely to revolutionise agriculture. It is to be a new 
point of departure, a “new dispensation.” ‘Is there 
not a bonanza (a mining term for peculiarly rich ore) in 
the farms with this new enterprise? Will it not give the 
farmer such profits, with less labour, as will enable him to 
be more independent? Is it not going to create new 
interests with our sons, when they can find a more profit- 
able employment, with less hard labour than can be found 
in any business in our cities?” It is to double the popu- 
lation of ‘four New England cities,” and indeed appears 
to be a veritable £7 Dorado for farmers. 
In thus introducing ensilage to the attention of his 
countrymen, Prof. Rogers is scarcely cautious in the 
manner in which he discounts the value of scientific and 
especially of chemical opinion upon this subject. “ En- 
silage is to be the food of the future for pigs and poultry 
