124 
NATURE 
[Fune 1 5, 1871 

The fossil plants are, as might be expected, very numerous, 
and many of them are well known through the memoirs, 
as well as the fine monograph on Fossil Plants, by Dr. | 
Schimper. 
In thus noticing some of the chief objects which | 
attracted our attention during a visit to this Mu- 
seum in January last, it is well also to remember that 
this grand collection owes its very existence to the life- 
long labours of Dr. Schimper. Since 1838 he has been 
the Director of the Museum, which before that time 
existed only in name. Throughout the terrible bombard- 
ment the Museum escaped almost without any damage, 
and has now become one of the most valuable prizes of 
war gained by the conquerors. The thanks of the world 
of science are due to the excellent director of this collec- 
tion, for all that he has done for it and for science, and 
we hope we are not wrong in here expressing the wish 
that, should Prof. Schimper, having been all his life a 
Frenchman, find it impossible to change his nationality 
and so continue to reside in Strasbourg, that that new 
rule which. knows so well when it likes how to appreciate | 
the man of science, will not forget to whose care it is 
indebted for the magnificent prize which it has won. 
Bove 

DUST AND SMOKE* 
FTER a few preliminary experiments illustrative of 
the polarisation of light, Prof. Tyndall adverted to 
the polarisation of light by fine dust, by the sky, and by the 
coarser particles of smoke. In the former the direction of 
maximum polarisation, as in the case of the sky, is at right 
angles to the iluminating beam. In the latter, according to 
the observations of Govi, the maximum quantity of polarised 
light was discharged obliquely to the beam. Govi’s ob- 
servation of a neutral point in such beam, on one side 
of which the polarisation was positive and on the other 
side negative, was also referred to. The additional 
fact was then adduced that the position of the neutral 
point varied with the density of the smoke. Beginning, 
for example, with an atmosphere thickened by the dense 
fumes of incense, resin, or gunpowder, and observing the 
neutral point, its direction was first observed to be in- 
clined to the beam /owards the source of illumination. 
Opening the windows so as to allow the smoke to escape 
gradually, the neutral point moved down the beam, passed 
the end of a normal drawn to the beam from the eye, and 
gradually moved forward several feet down the beam. 
The speaker did not halt at these observations, they were 
introduced as the starting point of inquiries of a different 
nature, anc after their introduction the discourse proceeded 
thus :— 
But what, you may ask, is the practical good of these 
curiosities? And if you so ask, my object is in some 
sense gained, for I intended to provoke this question. I 
confess that if we exclude the interest attached to the 
observation of new facts, and the enhancement of that 
interest through the knowledge that by-and-by the facts 
will become the exponents of laws, these curiosities are 
in themselves worth nothing. They will not enable us 
to add to our stock of food or drink or clothes or jewellery. 


of other things. But what have they to do with the 
animal economy? Let me give you an illustration to 
which my attention has been lately drawn by Mr. George 
Henry Lewes, who writes to me thus :— 
“T wish to direct your attention to the experiments of 
von Recklingshausen should you happen not to know 
them. They are striking confirmations of what you say 
of dust and disease. Last spring, when I was at his 
laboratory in Wiirzburg I examined with him blood that 
had been three weeks, a month, and five weeks, out of the 
body, preserved in little porcelain cups under glass shades. 
This blood was living and growing. Not only were the 
Amceba-like movements of the white corpuscles present, 
but there were abundant evidences of the growth and 
development of the corpuscles. I also saw a frog’s heart 
still pulsating which had been removed from the body 
(I forget how many days, but certainly more than a week). 
There were other examples of the same persistent vitality 
or absence of putrefaction. Von Recklingshausen did not 
attribute this to the absence of germs—germs were not 
mentioned by him ; but when I asked him how he repre- 
sented the thing to himself, he said the whole mystery of 
his operation consisted in keeping the blood free from 
dirt. The instruments employed were raised to a red 
heat just before use, the thread was silver thread and was 
similarly treated, and the porcelain cups, though not kept 
free from air, were kept free from currents. He said he 
often had failures, and these he attributed to particles of 
dust having escaped his precautions.” 
Prof. Lister, who has founded upon the removal or 
destruction of this “dirt” great and numerous improve- 
ments in surgery, tells us of the effect of its introduction 
into the blood of wounds. He informs us what would 
happen with the extracted blood should the dust get at it. 
The blood would putrefy and become fetid, and when you 
examine more closely what putrefaction means, you find 
the putrefying substance swarming with organic life, the 
germs of which have been derived from the air. 
Another note which I received a day or two ago has a 
bearing particularly significant at the present time upon 
this question of dust and dirt, and the wisdom of avoiding 
them. The note is from Mr. Ellis, of Sloane Street, to whom 
I owe a debt of gratitude for advice given to me when 
sorely wounded in the Alps. “I do not know,” writes 
Mr. Ellis, “whether you happened to see the letters, of 
which I enclose you a reprint, when they appeared in the 
Times. But I want to tell you this in reference to my 
method of vaccination as here described, because it has, 
as I think, a relation to the subject of the intake of or- 
ganic particles from without into’the body. Vaccination 
in the common way is done by scraping off the epidermis, 
and thrusting into the punctures made by the lancet the 
vaccine virus. By the method I use (and have used for 
more than twenty years) the epidermis is lifted by the effu- 
sion of serum from below, a result of the irritant cantha- 
radine applied to the skin. The little bleb thus formed is 
pricked, a drop of fluid let out, and then a fine vaccine 
| point is put into this spot, and after a minute of delay it 
| is withdrawn. 
But though thus shorn of all usefulness in themselves, | 
they may, by leading the mind into places which it would 
not otherwise have entered, become the antecedents of 
practical consequences. 
illuminated dust, we may ask ourselves what it is. How 
does it act, not upon a beam of light, but upon our own 
lungs and stomachs ? 
practical character. We find on examination that this 
dust is organic matter—in part living, in part dead. There 
are among it particles of ground straw, torn rags, smoke, 
the pollen of ilowers, the spores of fungi, and the germs 
* Lecture delivered at the Royal Institution, Friday evening, June 9, 1871. 
In looking, for example, at this | 
The question at once assumes a | 
The epidermis falls back on the skin and 
quite excludes the air—and not the air only, but what the 
air contains. 
“ Now mark the result—out of hundreds of cases of re- 
vaccination which I have performed, I have never hada 
single case of bloodpoisoning or ofabscess. By the ordi- 
nary way the occurrence of secondary abscess is by no 
means uncommon, and that of pyzmia is occasionally ) 
observed. I attribute the comparative safety of my 
method entirely, first, to the exclusion of the air and what 
it contains ; and, secondly, to the greater size of the aper- 
tures for the inlet of mischief made by the lancet.” 
I bring these facts forward that they may be sifted and 
| challenged if they be not correct. If they are correct itis 
needless to dwell upon their importance, nor is it neces- 
sary to say that if Mr. Ellis had resigned himself wholly 

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