March 30. THE COTTAGE GARDENER, 495 
one side to the wall; and as it was not long enough to 
reach the ground, a slight rail was put up to fasten it 
to on the other side, and then, from thence to the 
ground, mats and netting were fixed lengthwise.—R. 
In a former paper we suggested some analogies between 
the facts connected with the propagation and dissemi¬ 
nation of cholera,, and those laws under which certain 
minute organised growths, as funguses, blights, and the 
like, are admitted to exist and spread. We have ventured 
to refer, also, to the old Jewish ordinances respecting 
the leprosy, which, according to the authorities cited by 
us, were not opposed to our present impressions on the 
subject of contagion generally. 
The following is a summary of the whole of our 
present knowledge upon this subject, carefully collated 
from the report of Baly and Gull, to which we have 
already referred. We are not without hopes that our 
readers will now, at least, be able to form for themselves 
a sufficiently accurate notion of the matter to guide 
them in all things which pertain to their own conduct; 
and, indeed, much more accurate than many impressions 
upon which they are continually obliged to act in their 
daily concerns. 
The foregoing enquiry has been directed to the dis¬ 
covery of the relation borne by the atmosphere to the 
spread of cholera. The results arrived at lend much 
support to that theory of the cause of Cholera which 
regards it as a morbific matter or poison reproduced in 
; the air, and diffused in part, at least, by atmospheric 
currents. Such a poison brought by the atmosphere to 
this country might soon bo dispersed over many parts 
of it, and would meet with a suitable nidus for its re¬ 
production in the lower districts near the mouths of 
rivers, while in parts where tho atmosphere from its 
dryness and purity failed to afford the necessary con¬ 
ditions for its increase or maintenance it would perish. 
The unequal distribution of the disease in the winter 
of 1848-9, would, therefore, be quite intelligible. Its 
absence, in some parts, where the conditions of un- 
liealthiness abounded in towns and other inhabited 
places, would be accounted for; since the supposed 
poison, if it did not perish before it reached these inland 
or more elevated districts, would find then a [general] 
atmosphere unfit to preserve its active properties, and 
to communicate it to the [particular] spots in which it 
could increase and produce its effect on the inhabi¬ 
tants. The comparative intensity over other parts, for 
short periods, in the same season, would also be in¬ 
telligible ; likewise, the lingering of the disease in the 
spring of 1849 in certain spots distinguished for the 
most part by the local conditions productive of a damp 
and impure air. 
The renewed rise of the epidemic in the summer 
might be reasonably referred to the increase of impurity 
and moisture in the air under the influence of a rising 
temperature, and, perhaps, other meteorological con¬ 
ditions ; to the consequent increase of the poison in 
localities where it already existed; to its distribution by 
the air from these foci to other places more or less 
distant; to its increase in these again, if they afforded 
the necessary conditions; and its further diffusion. Thus 
the extent of the disease over the country, and its in¬ 
tensity in each large town, would continue to increase 
together, and the climax would be reached everywhere 
nearly at the same time. Lastly, when with the fall of 
temperature the atmosphere had begun to lose the pro¬ 
perties favourable to the transmission of the poison, 
comparatively few fresh places would become affected, 
and the epidemic would gradually subside. 
At the beginning of summer the poison would find 
the means for its dissemination, and increase soonest 
where the sources of damp and impurity most abound. 
Towns in such parts would soonest becomo foci (whence 
it would spread to towns in the more elevated and 
more inland regions), and in the autumn and begin¬ 
ning of winter would likewise continue longest, to 
afford an atmosphere fitted to transmit the poison from 
spot to spot, and, inasmuch as the epidemic is main¬ 
tained in each town by successive outbreaks in different 
localities, it would be expected to survive to the latest 
period whore the conditions for the transference of the 
poison from one place to another existed longest. The 
exceptions to the order of attack, both of tracts of 
country and of towns, are equally in accordance with 
the theory ; the purer atmosphere of elevated tracts of 
country rendering it difficult for the poison to reach the 
damp and foul localities in which it might increase and 
produce effects on the inhabitants. The late appearance 
of the epidemic in some coast districts scarcely offers 
greater difficulty; the state of the atmosphere varying 
in different parts of the coast at the same time, and in 
the same part at diffierent times; the morbific matter, 
while spreading rapidly over one such district, might be 
excluded by the state of the atmosphere from another 
not far distant one. 
The character of having the properties not of a 
gaseous substance, but of a matter in the form of solid 
or liquid particles, has already been assigned to the 
cholera poison. Such a poison being distributed only 
partially through the air, and carried hither and thither 
by atmospheric currents, might for a long time fail to 
reach a spot which was itself even well fitted to afford it 
the means of increase. 
The climax of the epidemic was more nearly simul¬ 
taneous in the different localities at the season and in the 
area most remarkable for impurity of atmosphere. For 
in an atmosphere uniformly or very generally impure 
the poison would find, in all parts of a given area, an 
equal medium of transmission from spot to spot, and, 
consequently, would increase everywhere equally, and 
reach the climax in all at or about the same time; as in 
the case of the registration districts of London (see 
pages 93, 94 of Report). But in the air not generally so 
impure, the transmission of the poison would be de. 
pendent on and more interfered with by accidental 
circumstances. Lastly, the fact, that around the more 
considerable foci slighter outbreaks occurred in places 
which from natural site or sanitary conditions had no 
