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13
his older and worse arranged slieds not suffering until a later period; and,
generally speaking, it turned out that 6ome of the very worst managed sheds,
as for example, Webb's, Humphrey's and Cook's were not attacked for several
months. The causes which led to the selection by the disease of one shed in
preference to another were in fact exactly similar causes to those which determine
the preference shown by scarlet fever, cholera, or any similar zymotic
disease for one house or family rather than another, and lead forcibly to the
conclusion that, given a certain infectious material, it will take effect only when
introduced in some way from without, and then the more readily the more certain
predisposing influences co-exist and operate.* What these localising circumstances
are appears from a full table relating to all the sheds in our parish, which I furnished
to the Commissioners, and which is published in the appendix to their Second
Report, (p. 67), and from the following statistical analysis of the facts observed.
A. Relation of size of establishment to outbrenl; of disease.
Of 35 establishments containing less than 10 cows, 22 were attacked, or 62 . 8 per cent.
22 „ „ 10 to 20 „ 15 „ 68.1 „
6 „ „ 20 „ 40 „ 5 „ 83 . 3 ,,
5 „ „ 40 „ 400 „ 5 „ 100.0 „
The liability to suffer, increasing with the number of cows kept, favours the view
that attributes the origin to contagion, since large cow-keepers buy in now cows
more frequently than others and are thus more likely to introduce disease into their
sheds.
B. Relation of Cleanliness or Dirtiness to Outbreaks.
Of 53 establishments habitually clean 37 were attacked or 69.8 per cent.
„ 14 „ „ dirty 10 „ „ 71.4 „
The difference is not sufficient to establish any connection between outbreaks
and mere want of cleanliness.
C. Relation between Crowding in Sheds and Outbreaks.
Of 44 sheds affording 200 to 600 cub. ft. of space per cow 35 were attacked or 79.5 pr.cnt.
»20 ,, „ 600 ,,1000 „ ,, 14 ,, 10.0 „
„ 9 „ „ 1000 and upwards „ 4 „ 44.4 „
This is in favour of crowding as promoting outbreaks. Distributing the above
instances into groups, according to the size of the establishment, it comes out that
the influence of crowding is only perceived distinctly in the smallest establishments.
In the larger establishments other causes may have operated more forcibly.*
* "The theory that the disease originated in the London cow-sheds is inconsistent, not only with the
evidence appended to our First Report, but with that which we have since received. The careful observations
made by Dr. Ballard, Medical Officer of Health for St. Mary's, Islington, confirmed by those of the Medical
Officers for Marylebone and St. Pancras, and the experience of other metropolitan districts, arc in direct
conflict with this theory, and point distinctly to contagion as the means by which the plague was originated
and propagated in London."—Second Report of the Cattle Plague Commissioners, (p. v.).