Vol. XXV. No. 7.] 
POPULAR SCIENCE NEWS. 
107 
fl?edieine arj)d pl^arFRactj. 
L 
THE MYSTERIES OF CONTAGION. 
A WELL-KNOWN lecturer has suggested as an 
improvement upon the present order of things, 
tliat lie "would make health catching, instead of 
disease," and while such an arrangement would 
undoubtedly be a very desirable one, the irre- 
futable logic of facts is against its possibility. 
Tlie whole matter of contagion and infection, 
liowever, is so mysterious and little understood 
that on theoretical considerations alone tlie com- 
munical)ility of health would seem to be as liliely 
as that of disease. The recent spread of "la 
grippe ■' has been an excellent illustration of how 
little is known on this point, for, notwithstanding 
the volumes that have been written upon the mat- 
ter, and the careful observations of trained phy- 
sicians upon thousands of cases, practically noth- 
ing hag been discovered in regard to its origin, 
nature, dissemination, or treatment. A disease 
which, starting from an uncertain point in Asia 
or Europe, can in a few montlis spread over the 
civilized world, attacking a large proportion of 
the population, is certainly a remarkatde one ; and 
the mystery of its progress is not the less remark- 
able from the fact that, apparently, it is not di- 
rectly communicated from one person to another, 
— like the small-pox, for instance, — but the malign 
Influence seems to l)e, as it were, in the air, and, 
like the rain, to fall upon the just and unjust, 
without any regard to their ordinary condition of 
health. One can hardly consider witli equanimity 
the result of the recent epidemic if it had been of 
a slightly more malignant and fatal type; but 
there is no apparent reason why it might not have 
been so, and produced a more devasting pestilence 
than any yet recorded in history. 
Diseases like typhoid and scarlet fevers, diph- 
theria, measles, or whooping-cough are considered 
to be dependent upon a specific germ of the dis- 
ease, received into tlie system from some previous 
case; but every physician has met with cases 
where no possible source of contagion could be 
traced, although under the conditions of modern 
life, with the constant intercommunication of per- 
sons, it is difllcult to prove that the disease did not 
have an external source. We have known of two 
cliil Iren residing on a lonely farm to be taken 
witii scarlet fever, althougli they had not left the 
ueigliborhood for weeks. In a family which had 
spent several weeks at a summer resort, one only 
was attacked with typhoid fever on returning 
home, aud yet all the members must have been 
eiiiiiilly exposed to the defective drainage or con- 
taminated water supply, if any such existed. 
Thousands of persons are today diinking impure 
water, living in an atmospliei'c saturated with 
sewer gas, and exposed to every unhygienic influ- 
ence, aud yet wliat a small proportion will ever 
contract one of the so-called " filth diseases." 
No view is more generally accepted than that 
low, wet, swampy localities are malarious and 
unhealthy ; yet Stanley, in his work on " The 
Congo," tells us that the station of Vivi, built on 
a liigh, well-<lrained bluflt', overlooking the river, 
and especially selected for its salubrious position, 
was one of tlie most unliealthy places in the whole 
valley, while at Equator station, only a few feet 
above the river, and surrounded by swamps filled 
with vegetable and animal matter putrefying uu- 
dei' tlie rays of the tropical sun, the men became 
strong and lieaity and in much better condition 
tliau at stations presumably much better adapted 
for a wliite man"s residence. 
Mr. Walter Coote, who travelled extensively in 
the South Sea Islands, gives the following similar 
evidence : 
"I have seen Englishmen living in Fiji, on the 
borders of almost stagnant estuaries, with the 
densest and most rank vegetation around them on 
all sides, with mosquitoes and a hundred such 
insects infesting the district like a plague ; in dry 
seasons their liouses will stand in the very center 
of great plains of reeking ooze, in times of flood 
the muddy river will rise to their very verandas, 
and yet these people are robust and healthy. I 
have gone from there, and a few weeks later vis- 
ited islands in the Solomon group, or New Heb- 
rides, where I have found a dry coral soil and 
liigh land, upon which the pure trade wind blows 
freshly month after month, steep land, too, from 
which the rain water is quickly borne downward 
to the sea, and all this but a few hundred miles 
from the Fiji group, and in the same latitude, and 
blown upon by the same trade wind, and yet in 
these places it is almost death for a white man to 
spend more than a few months in the year on 
shore, and practically no one who lives ashore at 
all can hope to escape frequent and severe attacks 
of fever. In fact, it is only by being thoroughly 
acclimated, through a long period of time, that he 
can hope to live there at all." 
Individual resistance to contagion is none the 
less remarkable. A physician or nurse will be 
brought into the most intimate contact with a 
case of contagious disease without contracting it, 
while the same patient may communicate it to 
a person passing him in the street, in the early 
stages of his trouble, before it has developed suf- 
ficiently to cause any alarm. We have known of 
a most malignant attack of diplitheria, communi- 
cated to a druggist by a person calling at the 
store before his disease had fully declared itself ; 
and a lady suftering from the mumps succeeded in 
communicating them to a sympathizing neighbor 
who stopped for a moment at tlie door to inquire 
after her health, while other members of the fam- 
ily residing in the same house remained unaf- 
fected. 
Although there is much in regard to contagion 
that is mysterious and not well understood, the 
fact remains that a certain class of diseases are 
directly communicated from one person to another, 
and that liad water, impure air, and unhygienic 
surroundings will often produce a class of diseases 
which otherwise could be avoided ; and if there 
are apparent exceptions to these rules it is none 
tlie less the duty of everyone, both to himself and 
others, to prevent the spread of contagious dis- 
eases by isolation ami disinfection, and to use his 
best efi'orts to prevent the development of such 
diseases by a careful attention to the cleanliness 
and sanitary condition of his surroundings. We 
are unable to do much more than this with our 
present knowledge, but medical science is making 
such progress in this direction that we may at 
some not very distant period be able to protect 
ourselves against the whole list of contagious dis- 
eases as easily as we do now against that scourge 
of previous centuries — the small-pox. 
[London Pharmaceutical Journal.] 
THE TEETH IN RELATION TO HEALTH.* 
BY W. KUSIITON, L. D. S. 
FiKST of all, let us inquire wliat the teeth are. 
They consist in the human adult of thirty-two 
masses of ivory-like substance, differing in size 
and sliape, and inserted in the bone of the upper 
aud lower jaws (sixteen teetli in each jaw) iu the 
*Rea<J before the Chemists' 
London. 
AgslBtants' Association of 
form of elliptical arches. The upper arch is nor- 
mally larger than the lower, the latter tieing inside 
the former when the mouth is closed, especially 
the incisors. The lower grinding teeth do not 
close against the corresponding teeth in' the upper 
jaw, tooth for tooth, but a lower tooth fits in be- 
tween the depressions between two upper teeth, 
and an upper tooth fits in between the cusps of 
the two lower teeth, so that when the teetli are 
closed the cusps are interlocked, and every tooth 
antagonizes more or less two teeth of the opposite 
jaw. The importance of bearing this fact in view 
will be seen later on. The bulk of the individual 
tooth is composed of a dense ivory-like substance, 
called dentine, which is covered on the root of the 
tooth by a substance almost identical with hard 
bone, called cementum, and covered on the crown 
by a coating of enamel. Enamel is the hardest 
tissue in the body, only containing from three to 
one per cent, of animal matter, being chiefly com- 
posed of carbonate and phosphate of calcium and 
magnesium, and fluoride of calcium. It is hard 
enough to strike a spark from steel like a flint. 
It would take too long to describe tlie formation 
of the teeth, l)ut it may interest you to know that 
the enamel is derived in the first place from the 
epithelium, or scarf-skin, aud is, in fact, modified 
skin, while the dentine, of which the bulk of the 
tooth is composed, is derived from the mucous 
layer below the epithelium. Lime salts are slowly 
deposited, and the tooth pulp, or "nerve," is the 
last remains of wliat was once a pulpy mass of 
the shape of the future tooth, and even the tooth 
pulp in old people sometimes gets quite obliter- 
ated by calcareous deposits. Of course, as you all 
know, the thirty-two permanent teeth are pre- 
ceded by twenty temporary, deciduous, or milk 
teeth. These are all fully erupted at about two 
to two and a half years old, and at about six years 
of age a wonderful process of absorption sets in 
liy which the roots of the temporary teeth iire re- 
moved to make room for tlie advancing permanent 
ones. The crowns of the former, having no sup- 
port, become loose .nnd fall away. One would 
naturally suppose that the advancing permanent 
tooth was a powerful factor in the absorption of 
its temporary predecessor, but we have many 
facts to prove it has no influence whatever; in- 
deed, the interesting phenomena of the eruption 
and succession of teeth are very little understood. 
I may remark in passing that a child of six who 
has not yet lost any temporary teeth, has in its 
jaws, either erupted or non-erupted, no less than 
fifty-two teeth more or less formed ; and the com- 
pact and convenient way in which they remain in 
the jaw ready to come down and take their place 
in their turn, is very beautiful. 
The two great uses of teeth are, briefly, masti- 
cation and articulation. For the former, the 
grinding back teeth (molars and bicuspids) are 
used ; for the latter, the incisive teeth (incisors 
and canines) are called into requisition ; and 
these, of course, are also used for biting or tear- 
ing food. In carnivorous animals all the teeth 
are of an incisive or cutting form, while those of 
herbivorous or graminivorous auiihals are broad 
and flat ; in carnivora the lower teeth close inside 
the upper ones, and so divide the flesh on which 
the animal feeds like a pair of scissors. In her- 
bivora, on the other hand, the teeth all the way 
round close on those of the opposite jaw like one 
millstone on another, and so give a good grinding 
surface, cutting teeth not being required. In man 
we have a comliination of both kinds of teeth, 
which leads us to believe (whatever the vegeta- 
rians may say) that man is intended to be an om- 
nivorous animal. 
