March 22, 1883] 
NATURE 
487 
introduced before the convulsions become too marked, it 
recovers. But when the pressure of oxygen is gradually 
raised above the normal, the animal again dies of convul- 
sions. This is evidently not the effect of mere increase 
in atmospheric pressure, but the effect of the oxygen on 
the animal, inasmuch as 25 atmospheres of common air 
are required to produce the oxygen convulsions, while 
3 atmospheres of pure oxygen are sufficient. This effect 
is readily explained on the hypothesis of interference by 
supposing that the absence of oxygen retards the trans- 
mission of impulses in the nerve-centres ; so that we get 
those which ought ordinarily to inhibit one another, 
coinciding and causing convulsions. Increased supply 
of oxygen gradually quickens the transmission of impulses 
until the waves first reach the normal relation, and then 
the normal rate being exceeded, the impulses once more 
nearly coincide, and convulsions are produced a second 
time. 
In discussing the action of the nervous system we have 
hitherto taken into account only that of the nerve fibrils, 
and left out of the question the nerve cells. We have 
assumed that the waves arrived in the reservoir (in our 
diagram) from a distance, and were simply transmitted 
along channels, but in the nervous system we have to 
take into account the origination of the waves in the 
nerve cells themselves, as well as their propagation along 
the nerve channels. 
There is a great difference between the function of the 
nerve cell and of the nerve fibre analogous to that which 
exists between the cell and the wire in a galvanic battery. 
The particular form of energy which we met with in both 
Cases originates in the cell and is transmitted along the 
fibre or the wire. In both cases also the energy appears 
to originate from chemical changes going on in the cell. 
Material waste of some sort goes on in both, and in both 
the products of this waste if allowed to accu nulate will 
by and by arrest the action. 
We find an indication of the difference between the 
amount of chemical change which goes on in the nerve 
celland in the nerve fibre in the amount of blood sup- 
plied to each respectively. The nerve cells are abun- 
dantly supplied with blood, and the nerve fibres very 
sparingly so. The free supply of blood secures to the 
nerve cells both the supply of fresh material and ready 
removal of waste products. 
Perhaps the best illustration that we can find in physics 
of the processes which take place in the nervous and 
muscular systems is however afforded by singing flames 
in which the sounds and movements are produced by 
very numerous small explosions: for both in the nervous 
and muscular systems the tissue change appears to go on 
as a series of small explosions. The material which 
yields nervous and muscular energy undergoes oxidation, 
but the oxygen concerned in the process is not derived 
directly from the external air. Substances which yield 
oxygen are contained within the tissues themselves just 
as nitre is contained along with oxidisable substances in 
a charge of gunpowder. 
: 
__ In this paper also we have spoken of waves of nervous 
interference as if they were simple, but it is much more 
probable that they are very complex, resembling much 
more the beats of sound produced by two singing flames 
which are not in unison, than simple waves of water. 
The number of nervous discharges which issue from 
the motor cells of the spinal cord during tetanus and set 
the muscles in action is, according to Dr. Burdon Sander- 
‘son, about 16 per second, but in all probability each of 
these impulses consists of a large number of small vibra- 
tions. In rhythmical actions, such as that of the respira- 
tion, we have probably at the very least three rhythms, 
Ist, exceedingly rapid vibrations in the nervous cells ; 
2nd, slower vibrations or beats from 16 or 18 per second, 
which issue from them and excite the muscles to action ; 
and 3rd, a still slower rhythm, of 16 per minute, probably 
due to interference between groups of cells, which leads 
to inspiratory movements alternating with rest or with 
active exspiration. The consideration of these com- 
plicated phenomena would, however, at present lead us 
too far, and they as well as the subject of nervous inter- 
ference in the heart and rhythmic contraction of muscles, 
must be reserved for another time. 
In this paper I must be content with the attempt to 
show that inhibition and stimulation in the nervous system 
are not dependent on special inhibitory or stimulating 
centres, but are merely relative conditions depending 
on the length of path along which the stimulus has to 
travel and the rate of its transmission. The test of the 
truth or falsehood of this hypothesis is to be found in 
the effect of alteration in the rapidity of nervous trans- 
Tnission upon inhibitory phenomena. The application of 
this test appears, so far as our present data go, to support 
this hypothesis. T. LAUDER BRUNTON 
BEN NEVIS OBSERVATORY 
N NATURE, vol. xxvii. p. 39, I gave a brief notice that 
on November 1—owing to stress of weather forbidding 
the regular daily ascents of Ben Nevis—I was obliged to 
discontinue the daily work of the meteorological observing 
system on the summit and slopes of the mountain. This 
was in simultaneous connection with my system of obser- 
vations near the sea-level at Achintore, Fort William. 
As in the previous summer, | had the honour to organise 
and carry on the work under the auspices of the Scottish 
Meteorological Society. The experience gained in 1881, 
when I first commenced observing on the Ben, enabled 
me to draw up and submit to the Society a more elaborate 
plan of mountain observation for the summer and autumn 
of 1832; and as I have been fortunate enough to carry it 
through for five months without any hitch, and as I am 
not aware that anything of the kind had, previous to my 
first undertaking, been attempted, I am naturally anxious 
that NATURE should have a more complete account of 
my last year’s operations. My plan was to have /ived 
stations at different altitudes between the main obser- 
vatories at the base and on the summit of the mountain. 
so placed in fact that I could observe regularly at half- 
hourly intervals during the daily ascent and descent of 
the Ben ; to extend the number of summit observations 
to five sets; and to have in every case simultaneous obser- 
vations taken at the sea-level station—my grand base of 
operations. All this was with a view to localising dis- 
turbances existing in the stratum of atmosphere between 
the sea-level and the top of Ben Nevis, to furthering 
meteorological research generally, and so ultimately to 
gain forecasting material. I arrived at Fort William from 
Edinburgh on May 25, and at once proceeded to give 
effect to my plans. During the next few days I was 
engaged mainly in erecting Stevenson’s thermometer 
screens, and laying out the sea-level station; in establish- 
ing a new “midway’’ observatory at the lake, erecting 
screen, and building there a granite cairn fora barometer ; 
and in reopening the temporary observatory on the sum- 
mit of the mountain. It was only by dint of great 
exertion and a gang of men that I got all in order 
on the top of the Ben on May 31. I had no occasion, 
however, to alter the arrangements of the previous sum- 
mer; and the heavy work of reopening chiefly consisted 
in digging out from the vast accumulations of snow the 
barometer cairn, hut, and thermometer cage which here, 
as a safeguard, incloses Stevenson’s screen. The snow, 
in fact, was nearly four feet deep, and it was necessary 
to cut out wide areas around the instruments. I also 
erected another screen to contain Negretti and Zambra’s 
self-registering clock-hygrometer, most kindly placed at 
my disposal by that eminent firm for the purpose of 
obtaining 9 p.m. values. I had also to fix a new roof of 
ship’s canvas to the rude shanty that affords some little 
