684 
physical problem, his searching questions 
were the qualities of untold benefit. He 
rarely delivered a lecture without calling 
attention to some subject which needed ex- 
perimental study ; he was never present at 
a meeting where scientific papers were read 
or discussed without pointing out some error 
or possible improvement in the method of 
experimenting. He was rarely on intimate 
terms with his students ; but no one came 
near him without recognizing his sweetness 
of character, his entire freedom from petty 
faults, his absolute unswerving devotion to 
the pursuit of truth, 
J.S. Amzs. 
JOHNS HopkKINS UNIVERSITY. 
IMMUNITY AND PROTECTIVE INOCULATION.* 
“When we search the history of the development 
of scientific truth we learn that no new fact or 
achievement ever stands by itself, no new discovery 
ever leaps forth in perfect panoply, as Minerva did 
from the brow of Jove. 
“ Absolute originality does not exist, and a new 
discovery is largely the product of what has gone be- 
fore. 
“We may be confident that each forward step is 
not ordered by one individual alone, but is also the 
outcome in a large measure of the labors of others. 
The history of scientific effort tells us that the past is 
not something to look back upon with regret—some- 
thing lost, never to be recalled—but rather as an 
abiding influence helping us to accomplish yet greater 
successes.’’—Sir Michael Foster. 
‘Again and again we may read in the words of 
some half-forgotten worthy the outlines of an idea 
which has shone forth in later days as an acknowl- 
edged truth.’’—Sir William MacCormac. 
TuHE fact that persons once afflicted with 
smallpox rarely experienced a second at- 
tack of that disease when repeatedly ex- 
posed to it was not only early observed, 
but made a matter of record by the Chinese 
long before the beginning of the Christian 
era. That the disease was contagious had 
long been a matter of common experience, 
* Address of the President of the Texas Academy 
of Science, given in the Chemical Theater of the Uni- 
versity of Texas, on October 26, 1900. 
SCIENCE. 
[N. 8S. Von. XIII. No. 331. 
and the means of protection against its 
ravages early became an interesting subject 
for investigation. 
The Chinese observed that when the dried 
and pulverized material from smallpox pus- 
tules was blown into the nostrils of persons 
who had not experienced an attack of the 
disease, the disease in persons thus in- 
fected underwent a milder course, was ac- 
companied by a lower death rate, and con- 
ferred immunity against further attacks of 
smallpox. This early method of protec- 
tion against the ravages of the disease be- 
came a common custom in China and 
India; but was later superseded by a more 
direct method of inoculation, that of in- 
troducing beneath the skin the scab of 
variolus pustules. The Chinese used the 
dried scab, the ordinary Hindoos the fluid 
pus, and the Brahmans pus that had been 
kept in wool for a period of twelve months. 
The last is clearly an instance of using 
attenuated virus. 
It should be remembered that smallpox 
extended westward to Europe during the 
sixth century, that it reached England 
toward the close of the ninth century, and 
at the time of the Crusades became wide- 
spread. In 1517 it was carried from 
Europe to Santo Domingo; reached Mexico 
in 1520, whence it spread throughout the 
New World. It was introduced into Ice- 
land in 1707 and to Greenland in 1733. 
It should be particularly noted, that in 
the invasion of new territory the virulence 
of smallpox at once became greatly inten- 
sified—in some instances nearly one-half 
the population being destroyed by it. Rob- 
ertson records the death of three million’ 
and a half of people in Mexico alone as the 
result of the invasion of 1520. Again, the 
dark-colored races seem to be more easily 
infected than Europeans. 
The protective method of directly inocu- 
lating the pulverized variolus scab beneath 
the skin slowly traveled westward; so 
