493 
December 21, 1872.] THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
epidemics. Why should small-pox die out in Ireland 
and then suddenly reappear and rage with great violence 
in many parts during the last twelve months ? How is 
it that cholera periodically invades the west from the 
east ? Why does an epidemic gradually increase in in¬ 
tensity, attain a maximum of virulence, and then gradu¬ 
ally die out F It is difficult to answer these questions 
satisfactorily, because all the factors concerned in the 
propagation of zymotic disease are not known. The 
unti-contagionists contend that small-pox and similar- 
diseases are propagated by other means than by emana¬ 
tions from the bodies of persons suffering from the 
diseases, and they believe that at particular times the 
condition of the atmosphere and of the constitution of 
the population are peculiarly favourable to the spread of 
these maladies. 
If it be admitted that, small-pox and certain other- 
diseases are sometimes caused by matters thrown off 
from the sick making an entry into the bodies of healthy 
persons, then the phenomena of epidemics may be shown 
to be explicable without abandoning the theory that 
small-pox and some other diseases are only communi¬ 
cable from individual to individual. We can readily 
understand that the low forms of life which produce 
epidemic and epizootic disease might, under favourable 
circumstances, multiply to a greater extent than usual. 
Under such circumstances the chances of their getting 
into the bodies of animals would be proportionally in¬ 
creased, and a local epidemic would be the result. In¬ 
tercommunication between the place where the germs 
were first developed and other places would soon scatter 
them over areas more or less considerable. During the 
siege of Paris small-pox germs largely multiplied in that 
city, because, owing to privation and depressing influ¬ 
ences of every kind, the population were rendered pecu¬ 
liarly susceptible to the influence of zymotic diseases. 
The stock of small-pox germs accumulated in Paris 
during the siege has since, there is little doubt, been 
distributed over a large part of Europe. 
In some epiphytic diseases we find the analogues of 
epidemic and epizootic maladies. The “blights’" in the 
cereals and other plants are caused by the ravages of 
minute parasitical fungi. A common disease of wheat 
grain is occasioned by the presence of the fungus Tire do 
caries , the seeds or sporules of which are so minute that, 
according to Bauer, a single grain of wheat may contain 
4,000,000 of them. The fungi which produce the 
diseases of plants do not originate sporadically, nor are 
they ever found except as parasites. For years a whole 
locality may be absolutely or comparatively free from 
them, when suddenly those pests will appear and destroy 
whole crops. It is the same with respect to the ravages 
of plants by insects; suddenly the caterpillars of moths 
will appear in vast numbers in localities \\ here they had 
previously been very scarce. A few years ago the ex¬ 
tensive plantations at Dunsany Castle, county of Meath, 
became suddenly the abode of myriads of caterpillars, 
which speedily stripped the barks and leaves of a large 
proportion of the trees. On investigating the nature 
of the caterpillars, it was found that they belonged 
to a rare species of moth, which had never been ob¬ 
served in the locality before, but which occasionally 
appeared in large numbers in certain districts in 
England. Amongst the numerous bisects which ravage 
our gardens and fields, it is interesting to note that in 
the seeds of wheat there is occasionally found an infu¬ 
sorial animalcule, termed vibrio tritici. It is, however, 
very many times larger than the vibriones above re¬ 
ferred to. 
Pliytologists acknowledge that they cannot account 
for the sudden appearance of vast numbers of epiphytical 
fungi and other pests of the higher members of the vege¬ 
table kingdom; but their ignorance in that respect in 
no way detracts from the positive knowledge which they 
possess relative to these fungi and insects being the 
actual cause of epiphytical diseases. Unsuitable soils, 
excessive damp, and other causes predispose certain 
plants to succumb to the attack of parasites, but the 
germs must be at hand, for there is absolutely not the 
slightest evidence to prove that any of these fungi ori¬ 
ginate spontaneously. No matter how sickly a wheat 
plant may be, it could not suffer from the blight unless 
there are fungi to prey upon it. 
That which is true of what we may term epidemics 
amongst plants, also holds good with respect to epide¬ 
mics amongst animals. We do not as yet certainly know, 
though wo may venture on hypotheses, why the germs 
of disease long absent from a locality may reappear, and 
fructify to an extraordinary degree. But our want of 
information on this point is not the slightest obstacle in 
the way of our belief in the “germ theory” of zymotic 
diseases. On the contrary, to abandon this theory 
would bo simply to reject the only reasonable explana¬ 
tion as yet advanced as to the means by which contagion 
is propagated and maintained. If we give up this theory 
we lay ourselves open to the charge of being believers in 
the doctrine of spontaneous generation. 
If species of bacteria or similar objects are the contagia 
of certain diseases, then we can understand why it is that 
so many persons who are near small-pox and fever 
patients escape, whilst persons not in contact with the 
infected catch the disease. The bacteria thrown off from 
the bodies of the sick are not equally diffused throughout 
the aii- as a gas or vapour would be, but, for the most 
part, are scattered about on the clothes and on other 
solid surfaces, from which they may be conveyed to great 
distances without making their entry into the body of 
any one. Ordinary bacteria are not found floating about 
in the air : if proper precautions are taken an animal 
liquid may be exposed for months to the air and yet be 
found free from bacteria; whilst on the other hand, if 
the liquid bo allowed to comci nto contact with a wine¬ 
glass, or a wall, or ordinary water (unless the latter has 
been heated to a point at which animal life is impossible), 
it will soon teem with bacteria. Contagion in general 
is conveyed by means of clothes or other solid substances, 
and is rarely directly propagated through the air. In 
the Report on Yellow Fever, by J. C. Nott, which ap¬ 
pears in the Report of the Board of Health of the City of 
New Ycrk for the year 1870-71, page 388, that writer 
says, — 
“No evidence, I think, could be more complete to- 
establish the probability of a disease. All facts being- 
opposed to its contagiousness, I can come to but one 
conclusion, viz., that the germ may be closed up in 
trunks or boxes, or be shut 'up in the baggage car cf a 
railroad, transported from one point to another (as from 
Mobile to Grove Hill and Citronelle), and turned loose 
to propagate and do its work of destruction. The 
disease was equally fatal at Citronelle and Spring Hill. 
Contagionists will doubtless regard this as a case of 
communication by contagion, but from the facts that I 
have never seen anybody communicate the disease, 
where luggage was not taken with the patient, and that 
the disease generally goes everywhere that steamboats 
go from our infected ports in epidemic years, I see no 
other conclusion than the one I have before given, viz., 
that the germ is carried closed up with baggage, and not 
generated and communicated by personal contagion.” 
Dr. Nott believes that the germs of yellow fever are 
not bred within the bodies of men ; but still men carry 
about these germs in their clothes just in the same way 
that the nurse from a fever hospital conveys contagion 
from the sick to the healthy, without herself becoming- 
affected with the disease. lily friend, Professor Moore, 
has favoured me with the following letter, the facts con¬ 
tained in which show how the first cases of zymotics m 
towns originate:— 
“ Wexford Infirmary, March 5th, 1871. 
“ My dear >Sir,—A railway labourer, from Glasgow, 
came to Wexford on or about the 30th December, 1870 ; 
sickened on the 2nd January, and died of small-pox on 
