606 
terrestrial magnetism and its relations to the earth-currents, Polar 
lights, and solar energy. Prof. Bergmann, of Berlin, followed 
with some remarks on the relations of modern surgery to the 
treatment of internal ailments. After some formal proceedings, 
the third general sitting, and with it the fifty-ninth gathering of 
the German Naturalists and Physicians, were brought to a 
close, 
In a brief report of this nature it would be impossible to do 
more than refer in the most summary way to the work done in 
the several Sections, of which twelve were devoted to scientific 
and eighteen to medical subjects. Altogether 522 topics were 
discussed, and 155 demonstrations carried out. Most of the 
proceedings will be published in special scientific journals, and 
here it will suffice to mention more especially the remarkable syn- 
thesis of coniine, the poisonous alkaloid of hemlock, effected with 
surprising success by Prof. Ladenburg. Thanks to this achieve- 
ment, the artificial production of a vegetable alkaloid may now 
for the first time be regarded as successfully accomplished. In 
the physiological department the question of the localisation of 
the cerebral functions gave rise to an animated discussion, in 
which Profs. Hitzig, Munth, and Soltz took part. In the 
section devoted to the subject of scientific instruction, Prof. 
Haeckel pleaded strongly for a severer training in this branch 
of knowledge amongst young students. It may be mentioned in 
conclusion that, in connection with this meeting, an exhibition 
of scientific instruments, apparatus, and educational appliances 
was held in the apartments of the Academy of Arts and Sciences. 
There was a good show of instruments of precision, microscopes, 
electric, medical, and other appliances, which attracted a large 
number of visitors during the few days the exhibition lasted, 
from September 16 to 26, 
THE HARVEIAN ORATION 
R. PAVY, F.R.S., delivered the Harveian Oration at the 
Royal College of Physicians on Monday afternoon. After 
giving the directions marked out by the founder of the Oration— 
viz., to commemorate the benefactions that have fallen into the 
possession of the College and to search and study out the secrets 
of Nature by way of experiment—the orator alluded to the aug- 
mentation which the income from the endowment of the Croomian 
Lectureship has recently undergone, by which the amount ayail- 
able is raised from ro/. to 200/, per annum ; and to the sum 
(2000/.) bequeathed by the late Dr. Gavin Milroy. He next 
spoke of the course pursued by Harvey as set forth by Lord 
Bacon, in his ‘‘ Novum Organum,” or ‘‘true directions concern- 
ing the interpretation of Nature.” Instead of giving himself up, 
as others had done before him, to arguing out conclusions from 
accepted axioms, Harvey struck out, Dr. Pavy continued, into 
the hitherto untrodden path of inquiry—that of induction—and 
sought knowledge by a direct appeal to Nature through the 
medium of observation and experiment. ‘‘It were disgraceful,” 
he says, ‘‘ with this most spacious and admirable realm of Nature 
before us, did we take the reports of others upon trust, and go 
on coining crude problems out of these, and on them hanging 
knotty and captious and petty disputations. Nature is herself to 
be addressed, the paths she shows us are to be boldly trodden.” 
In the discovery of the circulation Harvey applied the principles 
of induction and argued upon them in a strictly logical way. He 
showed himself to be a good and careful observer, judged even 
by the standard set forth by John Stuart Mill on the process of 
observing. The experiments which Harvey conducted on the 
arteries and veins, to assist him in his inquiry, were founded upon 
a well-devised plan. Dr. Pavy next spoke of the new departure 
in physiology which Harvey’s discovery established, of the oppo- 
sition with which his views were received, and remarked that the 
high position in his profession he had attained did not suffice to 
secure his escape from the effect of the prejudice against innoya- 
tion entertained by the multitude. Aubrey tells us he had 
‘heard him say that after his book on the circulation of the 
blood came out he fell mightily in his practice ; twas believed by 
the vulgar that he was crack-brained, and all the physitians were 
against him.” Harvey lived, however, to see his doctrine gener- 
ally accepted. The orator next referred to one issue of research 
derived, he said, from the labours of the present day, which has 
already yielded much good and useful fruit and gives promise of 
yielding much more. ‘‘ Belonging to the realm of living Nature 
there are,” he continued, ‘small organisms, the existence of 
which we must have remained unconscious of in the absence 
NATURE 
[ Oct. 21, 1886 
of the aid of the microscope. These bodies are known 
by the name of bacteria or bacilli, and, while some differ- 
ence of opinion has existed, it is generally thought that 
they are organisms belonging to the vegetable king- 
dom. There is nothing in their appearance to strike the 
observer that they possess any significance, and yet by recent 
research it has been found that they play a most important part 
as constituents of the living world.” The experiments of Spal- 
lanzani, Schulze, and Swann, were next described by Dr. Pavy, 
the natural conclusion to be drawn from which, he said, ‘ goes far 
towards absolutely establishing that the air contains the germs of 
living organisms, and that it is these that constitute the source of 
the microscopic organisms found to become developed in the 
presence of organic matter, which some have contended take 
rise spontaneously. This view is supported by the researches of 
the present day, and nothing that would bear the scrutiny of 
strict investigation has ever been adduced against it. It stands 
at the foundation of our modern notions regarding the vé/e played 
by bacilli, and thus occupies a position of weighty importance 
with reference to the matter. The step from the action exerted 
by bacteria as agents exciting the decomposition of organic pro- 
ducts to that which brings them before us asa source of disease is 
not a large one. In the one case they lead to change which 
would not otherwise occur, and in the other they disturb the 
order of changes naturally taking place and thus induce an ab- 
normal state; and although there is nothing in their morpho- 
logical characters to show the reason, different trains of 
phenomena—in other words, different diseases—are occasioned 
by different kinds of bacilli. . ‘Through the indefatigable 
researches of Pasteur and others the distinguishing form and life- 
history of certain of these organisms have been clearly made out. 
Placed under suitab'e conditions, it has been found that they can 
be reared or cultivated artificially, and one of the most marked 
and important characters belonging to them is the enormous 
extent of self-propagating power they possess. This accounts for 
the rapid spread that is observed to take place of an infectious 
disease, if allowed to progress without controlling measures being 
brought to bear upon it. We have to deal, then, with something 
that lives and grows by virtue of a power pertaining to itself. 
Permit this living growth—this parasite, in fact—to become dis- 
persed and to enter the system of a living person, and presuming 
it has lodged upon a soil supplying suitable conditions for its 
development, it will thrive and multiply and give rise to a series 
of phenomena which the physician has no power to arrest. Once 
the bacillus is implanted and the disease established, all that the 
physician can do is to see that the patient has fair play—that he 
is kept under the most favourable conditions for battling success- 
fully against his enemy. What is to be philosophically aimed 
at, however, is to check the spread—to bar the transmission of 
the parasite from one person to another, by attacking it outside 
the body ; and this, with the application of the proper measures 
of disinfection, can with facility be done, but naturally the 
facility of preventing extension stands in proportion to the 
degree of limitation at the time existing. The spark of fire is 
with the greatest ease extinguished, but let it kindle into flame, 
and in proportion as the flame spreads the difficulty becomes 
greater to get the conflagration under. This is one way in which 
the attack upon the bacillus may be made, and the ravages 
of disease restrained. Another way, by quite a different line 
of tactics, preseats itself; and the knowledge of this is due to 
the researches that have been recently conducted. The vulner- 
able point to which I am alluding lies not in connection with the 
bacillus itself, but with the condition of the medium upon which 
it may chance to fall. It has been found that the parasite re- 
quires virgin soil for its growth. This observation stands in 
harmony with the result of common experience as regards dispo- 
sition to contract infectious disease. It has been from remote 
times generally known that a person who has passed through one 
attack of an infectious disorder is not liable to the same extent 
as before to become affected on exposure to contagion, An 
influence has been exerted giving rise to more or less protection 
being afforded against a recurrence of the disease. Now it 
happens that by certain means the bacillus may be brought into 
such a weakened state as only to occasion, when introduced into 
the system of an animal, an effect of a mild nature, not dangerous 
to life, instead of the ordinary form of disease ; but the effect pro- 
duced, and this is the great point of practical importance, is as 
protective against a subsequent attack as the fully-developed 
disease. There are two methods by which attenuation in viru- 
lence of the disease-producing organism may be brought about— 
. 
