Fune 29, 1871] 
NATURE 
165 

“Tn many respects the address shows a considerable ad- 
vance over previous discourses by the same lecturer on this 
subject. The fact that the dirt or dust is in large part inor- 
ganic and in large part ‘dead,’ is now put prominently for- 
ward. Prof. Tyndall has, in fact, profited greatly by the les- 
sons of Dr. Gull—we shall not venture to assume that it is 
by anything which we have had to say by way of comment 
upon his previous addresses—and does not now assume 
to tell us anything more about the nature of this dirt than 
we knew before. He proceeds only to reason upon the 
subject, deriving his information, however, chiefly from 
chance communications from various physiologists and 
medical correspondents. One correspondent tells him 
that ‘blood free from dirt’ will take longer to putrefy 
out of the body, and Von Recklinghausen’s experiments 
are brought in reinforcement of the still more striking 
results and experiments of Prof. Lister; another in- 
forms him that vaccination through a bleb raised by 
blistering is less likely to produce secondary abscesses 
than by the ordinary method; and Dr. Budd assures 
Prof. Tyndall that, ‘from the day when he first began to 
think of these subjects, he has never hada doubt that the 
specific cause of contagious fevers must be living 
organisms.’ The last is, of course, a very interesting 
proof of early wisdom, but is not of the nature of a strict 
demonstration. The circumstance mentioned by Mr. 
Ellis reminds us that we have, on the other hand, seen it 
stated in print by one gentleman that he had to abandon 
vaccination by blistering because it was, in his practice, 
more productive than any other of suppurative and inflam- 
matory accidents. But all this is really beside the ques- 
tion. The whole course of subcutaneous surgery, the 
whole range of Prof. Lister’s experience, the daily expe- 
rience of the difference in progress between simple and 
compound fractures, a thousand facts and observations, 
and the accepted and proved theories of surgical practice, 
have long convinced every surgeon that, in proportion as 
air and that which air bears are excluded from the fluids 
of open wounds, and from the organic fluids of the body, 
suppurative and putrefactive processes will be lessened 
and warded off. So much Prof. Tyndall might, so far as 
our profession is concerned, have taken for granted ; 
and if he chooses to read, for instance, such papers as 
those we have published of Adams on subcutaneous 
osteotomy, he will see how largely this knowledge affects 
our practice in other directions than those to which he 
has referred. But, after proving to us what we know, 
Prof. Tyndall takes a leap, and assumes precisely those 
conclusions which we are desirous of his aid in testing. 
All these facts are as much accordant with the doc- 
trines of Liebig and the experiments of Bastian, as with 
the doctrines of Schwann and the experiments of Pasteur. 
Granted that air-borne particles are prime agents in initi- 
ating putrefactive and fermentative change, is this by a 
development of pre-existent living germs, a growth of 
deposited ova, or by a communicated molecular motion of 
dead organic matter in a state of change? Is it from germs 
or from fermentative organic particles ? We wish we could 
see that Prof. Tyndall had advanced our knowledge at 
all concerning this, the central knot of the tangle. It does 
not help us when he quotes certain known examples of 
parasitic disease, such as arises from pébrine. Because 
the itch is the result of the activity of the acarus, it does 
not follow of course that all skin-diseases are parasitic. 
Mr. Tyndall declares indeed, that the successful workers 
and profound thinkers of the medical profession are daily 
growing more convinced that ‘contagious disease gene- 
rally is of the same parasitic character’ as the silk-worm 
disease. We cannot find on what he bases that very 
broad statement. Where are the works of the ‘most suc- 
cessful workers and profound thinkers’ which support 
that statement? It will be very kind of the lecturer to in- 
form us whom he thus dignifies, and to what growing 
Series of authorities he refers. Certainly not to the re- 

searches on cholera of Gull, Baly, or Cunningham and 
Lewes : these negative the parasitic theory. Salisbury 
started a parasitic theory for measles, but his observations 
have been generally discredited, if they were ever ac- 
cepted. Hallier’s observations have certainly not gained 
in authority by the results of many recent investigations 
such as those of Burdon Sanderson. We are not aware 
of a parasitic theory of scarlet fever being held by any 
one. The theory concerning typhoid fever, which Dr. 
Budd holds strongly and defends ably on purely logical 
grounds, is as distinctly controverted by Dr, Murchison, 
“Prof. Tyndall, however, lays just stress upon one im- 
portant aspect of the question, which is precisely that 
which has long fascinated medical observers, and which 
is of the deepest importance. To it also, however, he 
adds nothing ; and from it he draws, with admirable and 
unquestioning boldness, precisely the conclusions as to 
which we have all been debating whether they be the true 
and only conclusions. Small-pox and scarlatina are, to 
use the graphic words of Miss Nightingale, in ordinary 
medical experience, ‘dog and cat,’ so that one cannot 
change into the other any more than Tabby can give birth 
to Fido. When she says that she has seen with her own 
eyes one or other spring up in a corner of a room from 
neglected dirt, Miss Nightingale uses, of course, a purely 
figurative language, and her evidence must be taken 
guantum valeat, But when Mr, Tyndall declares, on the 
other hand, that zymotic diseases are all of primal inheri- 
tance—long descended primeval germs, never changing, 
never dying out, and ever passing on by lineal descent— 
he treads also upon ground less secure than he supposes, 
That this is the ordinary observed mode of extension of 
contagious diseases no one will dispute. That they have 
no other many will dispute. When he declares that, for 
the similarity or identity of effect of like particles acting 
on like fluids, we have no physical parallel, he obviously 
leaves out of view the whole series of phenomena of 
crystallisation from saturated fluids. 
“To sum up: The tendency of modern research is cer- 
tainly not so favourable as Mr. Tyndall believes and ex- 
pects it to be to the theory of the parasitic origin of con- 
tagious disease. We should rather declare it to be un- 
favourable to that theory. The theory of the permanency 
and unrelated individuality of zymotic types of disease is 
not, as he assumes, an undisputed or unquestioned theory. 
We have to set against it, first, the theory of the correla- 
tion of zymotic diseases, which is growing into importance, 
and likely to attract more attention now than heretofore ; 
second, the observations of statisticians of the comple- 
mentary character of epidemics of zymotic diseases, and 
their apparent interchangeability in periods of decline; 
the theories of the spontaneous origin of zymotic disease 
by no contemptible observers, and in diseases as distinctly 
communicable as typhoid ; and the observations, experi- 
ments, and reasonings of Pouchet and of Bastian, which 
have not yet been met, and which cannot be disposed of 
by a few words of philosophic doubt. We appreciate 
very highly the value of Prof. Tyndall’s assistance in 
solving these questions. We entirely concur in his 
opinion that, as a physicist, he has a great power of use- 
fulness in this field of investigation ; and, if we refer him 
to the work of Gull, Baly, Cunningham and Lewes, Farr, 
and Murchison, it is because we are desirous that he 
should not be content to win easy triumphs with audiences 
uninstructed in the questions he discusses, or with the 
partisans of the theory he has adopted, but that he should 
enter into the heart of the question and face its real 
difficulties. It would be infinitely satisfactory if we could 
all arrive at as simple a sole theory of disease as that 
which Prof. Tyndall accepts entire, symmetrical, and 
rotund, from the supporters of the germ-theory ; but we 
fear the solution is not yet in hand. It is satisfactory to 
have enlisted his sympathies, and we shall all be glad of 
| his solid and sincere assistance.” 

