Fune 26, 1873) 
NATURE 
161 
Zoological Section as the result of the present year’s work ; 
the anatomical department of this section has, however, 
made a fair start under the direction of the late member, 
Mr. A, G. Burchardt. W. B. Lewis’s Report of the 
Geological Section, with accompanying plates, shows 
there has been some activity in this department. A. F. 
Buxton’s Entomological Report consists of a complete 
list of the Lepidoptera which have been noticed within 
eight miles of the School Close. Under Mr. Kit- 
chener’s, the President’s, guidance, some good work 
has been done in the Botanical Section, though the 
workers seem to be few. Appended to the report of this 
section is an abstract of two papers by Mr. Kitchener on 
a Pelerian form of Linaria vulgaris, On the whole, the 
« Report of this Society’s work for 1872, is one of which 
there is no reason to be ashamed, and we hope that each 
year will add to the number of those who take an active 
part in the work. From many scientific societies it is 
not advisable nor often expedient to exclude non-workers, 
but in such societies connected with schools, it should be 
insisted on that every member be an active worker : only 
thus can they completely serve the purpose for which 
they are established. 
LETTERS TO THE EDITOR 
[Zhe Editor does not hold himself responsible for opinions expressed 
by his correspondents. No notice is taken of ‘anonymous 
communications. ] 
Dr. Sanderson’s Experiments and Archebiosis 
Tue letter by Dr. Sanderson, in last week’s NATURE, coritains 
an interesting and important confirmation of my experiments, 
which I was very glad to see. There are two or three points, 
however, which seem to require some comment. 
In the first place the flasks and retorts after exposure to the 
heat were kept only from three to six days, before they were sub- 
mitted to examination in order to ascertain whether fermentation 
had or had not taken place. But in cases in which fluids are 
exposed to heat for a long time, or are exposed to higher tem- 
peratures, the process of fermentation is almost invariably delayed 
and also modified in intensity. It must not therefore be supposed 
that fermentation would not have taken place at all in certain of 
Dr. Sanderson’s flasks, simply because it had not occurred 
within four, five, or six days. : 
Secondly, Dr. Sanderson thinks his present experiments enable 
him to say that the particular fluid with which he experimented is 
not prone to undergo fermentation within six days, after it has 
been heated to a temperature of 100°92°C, I would ask Dr. 
Sanderson, however, whether he has been careful to observe the 
precise temperature attained by ‘an infusion boiling rapidly in a 
flask from which the steam can find exit only through a capillary 
orifice—as in the experiments which we performed together ? 
Thirdly, I think it very desirable that Dr. Sanderson should 
state definitely to the scientinc world what precise meaning he 
wishes to convey by his emphasized use of the word ‘‘ chance” 
in the concluding paragraph of his letter. There seems a little 
ambiguity in his use of the word, which is the more to be re- 
gretted, since it occurs in the statement of an inference— 
where freedom from all possibility of misconception is so 
eminently desirable. H. CHARLTON BasTIAN 
University College, June 23 
Spectrum of Nitrogen 
In a letter to NATURE (April 17th), Mr. Stearn throws some 
doubts on the accuracy of my experiments regarding the spectrum 
of nitrogen. I shall take the earliest opportunity of repeating 
and completing my experiments, and hope then to bring the ques- 
tion to a satisfactory close. As, however, some time may elapse 
before I can resume work, I wish to say now a few words in 
answer to Mr. Stearn’s letter. 
Before all, I wish to state clearly in what way the correctness 
of the opinion I profess with regard to the band-spectrum of 
nitrogen would be affected by an error introduced into my expe- 
riments. The unexpected result of an experiment of mine, to- 
gether with a remark which Plucker makes in one of his papers, 
suggested to me the idea that the so-called band-spectrum of 
nitrogen might be that of the oxides of nitrogen, Iwas confirmed 
Bite, 
in this idea soon afterwards by a remark of Angstrém in his 
recent paper on double spectra (Comptes Rendus, August 17, 1871, 
but which was omitted in the English translation), by which he 
calls attention to the close resemblance of this band spectrum 
with the spectrum of metallic oxides. I have described in my 
paper the experiment just mentioned. A rather narrow tube 
showed, when exhausted, the lines of nitrogen ; as soon as the air 
entered the bands appeared. The remark of Plucker alludes to 
the fact that a tube filled with oxides of nitrogen showed the 
bands with unusual brilliancy. In order to test the accuracy of 
this opinion I intended to make a crucial experiment by taking 
care to remove every trace of oxygen. I used for this purpose, at 
the suggestion of Dr. Balfour Stewart, small pieces of sodium 
heated in the vacuum tubes. The sodium was fused several times 
in succession in order to free it from impurities. When the nitro- 
gen was thus treated it always showed a line spectrum, the lines of 
which seemed to coincide with those of the known line spectrum 
of nitrogen when measured with the instrument at my disposal. 
It seems now that I have been too hasty in assuming that this 
apparent coincidence was a teal one. While passing through 
London a few weeks ago, Dr. Huggins was kind enough to allow 
me the use of his spectroscope in order to compare, under his 
supervision, the spectrum of my tubes with the real line spectrum 
ofnitrogen. Ithen found that, although my tube showsalinewhich 
is very near the principal double line of nitrogen, the spectrum is 
not that of nitrogen. I am at present unable to say what is the 
origin of this spectrum ; but I do not think that its formation 
can be brought forward as a proof that the band spectrum is not 
due to oxides of nitrogen. On the contrary, it rather shows that 
an impurity which has no effect on the spectrum of air, will have 
one when all the oxygen is removed, and that a change has there- 
fore probably taken place in the conducting power of the gas 
which gives out the spectrum. 
I donot quite see the real object of Mr. Stearn’s letter. If he 
merely wishes to say that the proof brought forward by me is 
insufficient, and that the question must still remain an open one, 
I confess I have nothing to say against it. If he, however, 
wishes to convey the idea that nitrogen has really a double spec- 
trum, I do not think his argument is a correct one. 
I will not trespasss any longer upon your space, but I may, I 
think, fairly ask your readers to suspend their judgment until I 
have completed my experiments. 
Heidelberg, May 30 ARTHUR SCHUSTER 
Ground Ivy 
WITH respect to the question started in the number for 
June 12 of this journal as to the Ground Ivy, it may be said that 
in Glechoma, as also in Origanum vulgare, Thymus serpyllum 
and vulgaris, and Mentha vulgaris, specimens having flowers 
with small corolla and undeveloped anthers are very common, 
I think as common as specimens having flowers with 
large corolla and the two sexes developed. Also of 
Mentha aquatica and Prunella vulgaris specimens with smaller 
corolla and only pistils developed are found, but much more 
rarely than those of the other form. 
I have attempted in my work to give an explanation of the 
origin of the second form of the above-mentioned Labiatz, as 
follows :— 
The species named are distinguished from our other 
Labiatee by the coincidence of the following three pecu- 
liarities :-— 
1. By an abundance of honey, and in consequence of that by 
an abundance of insects visiting and cross-fertilising them.” 
2. In the hermaphrodite flowers, by a stigma so far overtopping 
the anthers and developed so long after the anthers that self- 
fertilisation is impossible, or nearly so. 
3. By a great variability in the size of the corolla in the her- 
maphrodite flowers of different specimens. 
Now when the flowers on different stems of the same species 
differ in the size of their corolla, it is evident a priori, and 
ascertained by direct observation, that generally those with the 
largest corolla are the first seen and visited by insects flying near 
them, those with the smallest corolla the last. The latter, always 
the flowers last visited, are fertilised exclusively by the pollen of pre- 
viously-visited flowers, consequently produce their pollen in vain ; 
and since the non-production of useless organs is always an 
advantage to every organic being, varieties of the smallest 
* For instance, I found Tiymus serpyllum visited by 7 species of Apidz, 
3 species of Sfhegide, 14 species of Diptera, and 6 species of Lepidoptera ; 
Glechoma visited by 21 species of Apide, 8 species of Diptera, and 3 species 
of Lepidoptera. 
