381 
: The ten minutes are reckoned from the moment 
the liquid begins to bubble freely. 
The remarks of Dr. W. Roberts (NATURE, Feb. 20, p. 302) do 
cease boiling. 
therefore not apply to these experiments. Moreover, I observed 
i ie the temperature in the mouth of the flask, and found 
it always to be between 95° and 100°C. Therefore no part of 
the flask escaped the full effect of the germ-destroying heat. 
While the boiling continued, a heated piece of unglazed flat 
earthenware tile was then pressed on the mouth of the flask ; 
the solidified asphalt melted, and the piece of tile adhered, after 
cooling, firmly to the mouth of the flask. No air could then 
penetrate to the interior, except through the pores of the closing 
tile. The tile was 7 millimetres thick. 
The previous heating of the tile is necessary, not only for 
melting the asphalt, but also for destroying the germs which 
possibly may adhere to the tile itself. This heating is effected 
ina Bunsen’s burner, and raises the temperature of the tile to such 
an extent that a tuft of cotton-wool is scorched brown when 
pressed against it. The tile should not be too hot when it comes 
on the asphalt, lest the fumes arising from the decomposition of 
the asphalt should spread to the interior of the flask, and hinder 
the production of Bacteria. 
The flasks prepared in this way were then exposed in a water 
bath to a temperature of 39—35° C. After two or three days the 
liquid was very turbid, very often a thick pellicle appeared on 
the surface, and flocky masses were swimming in the solution. 
The closing tile was then removed by melting the asphalt, and 
the microscopic examination showed myriads of Bacterium termo 
in lively motion, while the pellicle and the flocky masses con- 
sisted also of these organisms. A/icrococcus crepusculum and Vibrio 
serpens were often present, but 3. termo predominated. (The 
Bacteria were determined after Cohn’s classification. ‘‘ Beitrige 
zur Biologie der Pflanzen, II.”) 
The experiment conducted in this way yields always a positive 
result. Now three things are possible :-~ 
1. The materials employed originally contained germs of Bac- 
teria, which have simply developed themselves. 
2. During the experiment germs have penetrated into the in- 
terior of the flasks. 
3. The Bacteria have originated de ovo in the liquid. 
The first explanation is not admissible. For control-solutions 
treated exactly in the same manner, but composed in other 
proportions, remained under the same conditions perfectly free 
from Bacteria. These solutions were— 
a. 100 c.c. of the above-named salt solution + I grm. am- 
monium-tartrate + I grm. grape-sugar. 
6, 100 c. c. of the salt-solution + I grm. ammonium-tartrate 
+ o'2grm. peptone. 
Both these liquids are eminently suited to the nutrition and 
growth of Bacteria. That they nevertheless remained pure from 
these organisms proves that zove of the materials employed con- 
tained germs capable of resisting for ten minutes a temperature of 
100° C. 
The second explanation is equally inadmissible. To prove 
this directly 1 grm. ammonium-tartrate was dissolved in 100 
c.c. of the salt solution. This liquid was equally divided in 
two flasks, A and B. To A was added a trace of air-dust, col- 
lected in a little room where putrefying liquids were often stand- 
ing, and then the flask was closed with a piece of tile in the above- 
described manner. B was boiled and closed as usual ; but on 
the upper surface of the closing tile a considerable quantity of 
the same dust was loosely strewn. After twenty-four hours A 
becomes turbid, and swarms on the third day with Bacteria ; B is 
on the eighth day still perfectly clear, and is then no longer exa- 
mined. ‘The conclusion is obvious: no germs of Bacteria do 
pass through the pores of the tile. 
_ The only remaining explanation, is, in my opinion, this : 
under the above-described circumstances, Bacteria can arise 
without pre-existing germs. Not in any single case have I seen 
any other organisms than Bacteria—never fungi. 
A certain concentration of the liquid is an important desidera- 
tum in these experiments. A specific gravity of about 1'o12 is 
the most favourable. Greater dilution is a hindrance as well as 
greater concentration—at least when the above-named materials 
are employed. It is, however, not absolutely necessary to employ 
grape-sugar for raising the specific gravity up to 1012. Common 
salt can do this just as well. Thus the following mixture is equally 
sufficient for generating Bacteria :—100 c.c, of the above-named 
salt solution, 2 grm, common salt, 0'2 grm. grape-sugar, 0°4 grm, 
peptone, ie : 
The first thing to be done now is to substitute for the 
grape-sugar and the peptone less complicated bodies. My ex- 
periments have been continued with this purpose. 
This brief abstract may suffice for the moment. Shortly a 
more detailed communication and discussion will appear in one 
of the special journals. D. Huizinca, 
Professor of Physiology at the University of Groningen 
Groningen, March 15 
The Janssen-Lockyer Method 
SINCE my letter which appeared in NATURE of February 20 
there has been a letter from Dr. Huggins (also in NATURE, 
February 27, p. 320), and I see that Mr. Richard A. Proctor has 
likewise published a letter in the Zvgdish Mechartic of March 7. 
With respect to the former of these communications I have but 
one remark to make. I was ignorant that the domestic bereave- 
ment to which Dr. Huggins alludes occurred at the time when 
the eclipse reports from India reached this country. This cir- 
cumstance undoubtedly explains why Dr. Huggins did not 
sooner make the observation ajluded to ; and had I known the 
coincidence in point of time between these two events I should 
not have made the remark to which he refers. 
Mr. Proctor’s letter certainly surprises me, especially as 
coming from one who holds a prominent official position in the 
chief astronomical society of this country. 
1. In the first place I cannot understand what Mr. Proctor 
means when he says with allusion to the question proposed by 
Mr. Lockyer in his preliminary paper of 1866—‘‘I have always 
judged from the form of the query that, as he now mentions, Dr. 
Stewart had suggested its wording.” If Mr. Proctor will refer 
to my letter in NATURE of February 20 he will find it stated 
that I advised Mr. Lockyer to introduce his views in the shape 
of a question, which he accordingly did. The wording was Mr. 
Lockyer’s own, being the result of his own cogitations on the 
subject, and all that I did-was to suggest the putting of it in the 
form of a question. 
2. Nor can I understand what Mr. Proctor means when he 
says— ‘‘ I can admit very readily that Mr. Lockyer clearly recog- 
nised the principle of the method for spectroscopically studying 
the prominences when he asked the query. I do not indeed see 
how any person at all familiar with spectroscopic analysis could 
have failed to do so, after reading Dr. Huggins’ account of his 
observations of T Coronz.” 
When Mr. Lockyer suggested the application of the spectre- 
scope to the sun’s red flames he knew, no doubt, and made use 
of his knowledze, that in white solar light the spectrum is scat- 
tered, while in light from incandescent gases it is not ; but his in- 
formation on these points was not surely derived from Mr, 
Huggins. Was not Newton the first to show that a slit of white 
light is dispersed by refraction into a broad band or ribbon? 
I do not know whether Newton ever clearly enunciated that in 
consequence of this dispersion the ribbon was less luminous than 
the slit. Perhaps he thought that this was sufficiently under- 
stood, but at any rate he who after Newton first made this an- 
nouncement cannot be said to have made a very startling dis- 
covery. I have the highest respect for the brilliant discoveries 
of Dr. Huggins, but I am quite sure that he does not claim as 
one of these the statement that ‘‘when the feeble light of a 
nebula is dispersed into a spectrum consisting of light of all re- 
frangibilities, the spectrum is extremely faint.” 
In like manner the man of science who first showed that incan- 
descent gases give out only afew spectral lines made a great dis- 
covery ; while he who after this discovery first announced that 
such light will not be weakened by dispersion can hardly be said 
to have made a discovery at all. 
Now these two discoveries of two different kinds of spectra 
have been most prolific. Swan has used them; Kirchhoff has 
used them in certain experiments of his in which the conditions 
were probably very similar to those in T Corone, and after 
Kirchhoff, Huggins, and after Huggins, Lockyer. Each of these 
and many more have applied those well-known principles in many 
ways, none of the observers claiming the principles, but each 
one claiming his own application, being at the same time per- 
fectly willing to acknowledge his neighbour’s just claims. For 
instance, Dr. Huggins says—‘‘ To Mr. Lockyer is due the first 
publication of the idea of the possibility of applying the spectro- 
scope to observe the red flames in sunshine.” Now this is pre- 
cisely the state of the case, and I need not say anything more. 
3. Then as to the advice to Mr, Lockyer to put his suggestion 
in the shape of a query, it ought to be remarked that it was a 
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