— 
May 6, 1886} 
INAD Uther 
23 
and the water acidified beforehand were connected with a gal- 
yanic cell and a telephone, then no interruptions of the current 
could be recognised during the time of the sounding. The 
contact of the water-jet with the plate must necessarily there- 
fore be continuous. Herr Baur deemed this mode of excitation 
very well adapted to the purpose of studying the vibrations of 
plates. In the discussion following this address it was pointed 
out from various sides that more than twenty years ago Prof. 
Tyndall and after him Magnus had instituted experiments re- 
specting the action of tones on water-jets, and that Prof. 
Tyndall had at the time shown his experiments to the Physical 
Society in Berlin. 
Physiological Society, March 12.—Dr. Gad reported 
on the experiments he had made on the subject of hzemor- 
thagic dyspnoea which he had referred to in his last ad- 
dress. If by opening a cannula inserted into the aorta 
a large supply of blood were taken from an animal, dog or 
rabbit, then dyspnoea at once ensued, and that in the form of 
increased inspirations, such as showed themselves in all cases of 
dyspnoea induced by insufficient conduction of oxygen to the 
respiratory centre. These heightened inspirations proceeded side 
by side with a conspicuous sinking of the blood-pressure, and 
were denominated by the speaker ‘‘ pneumatorectic” respira- 
tions. This respiration was distinguished from normal respira- 
tion by regular deep inspirations of unchanged frequency, 
inspirations in which the middle attitude of the thorax removed 
farther from the expiratory than was the case in normal respira- 
tion. The curve of respiration either then passed over into the 
normal, or convulsions set in,in which case the blood-pressure rose 
and the respiratory curve grew altogether irregular. After 
repeated heavy discharges of blood, the pneumatorectic passed 
into the ‘‘syncoptic” respiration, which was characterised 
by deep inspirations of very infrequent occurrence, during 
which the attitude of the thorax after expiration approxi- 
mated ever nearer to that which it held in a dead body, 
till the last breath, and so the death of the animal, 
occurred. These two kinds of respiration, the pneumato- 
rectic and the syncoptic, were perfectly regular and typical ; 
the former showed itself immediately after a heavy discharge 
of blood, the latter before death. Between these two extreme 
forms there passed a series of others in an inter-current manner. 
Of these there was first to be mentioned a very frequent super- 
ficial respiration, which was inadequate to the necessities of the 
organism, and had the name ‘‘hypokinetic” applied to it. If 
the animal recovered out of this stage, the hypokinetic passed into 
the pneumatorectic and the normal respiration, otherwise it was 
followed by the syncoptic respiration and death. ‘The transitional 
process from the hypokinetic into the pneumatorectic respiration 
might be experimentally brought about in a perfectly regular man- 
ner by the injection into the venous system of warm physiological 
solution of commen salts. With the increase of the blood-pressure 
the alteration in the form of respiration at once asserted itself, 
the respiration becoming sufficient. Even at the stage of syn- 
coptic respiration a transition into the pneumatorectic respira- 
tion might occasionally, though not always, be induced by 
injection of solution of common salt, and in that way the life 
of the animal be rescued. Another form of respiration 
following heavy bleeding was that which showed itself in 
periodical increasings of the amplitudes in respiratory move- 
ments. These and diminishings of amplitudes ran parallel 
to the Traube-Hering periodical oscillations of the curves 
of blood-pressure, though with displacement of the phases. 
The periodical oscillations in the amplitude of respiration 
referred to formed a transition to the Cheyne-Stokes pheno- 
menon. The speaker recounted the explanations of the Cheyne- 
_ Stokes respiration, and took sides with the older theory, 
_ according to which it was to be conceived as a rhythmus of 
activity on the part of the central organs having periods of a 
higher order than had the simple rhythmus of respiration. In 
conclusion Dr. Gad drew from his physiological experiences a 
series of practical consequences having respect especially to the 
suitability of transfusions of common salt after heavy bleedings, 
particularly at the stage of hypokinetic respiration. —Prof. Zuntz 
spoke of the nature of the stimulations regulating the normal 
_ respiratory movements. The every-day experience that increased 
muscular activity produced an increased respiratory activity, 
i dyspnoea, had suggested simultaneously to the speaker and to Dr. 
_ Geppert the idea of investigating whether the gases of the blood, 
r were universally assumed to be the sole stimulations of 
respiration, were adequate to the explanation of this dyspnoea, 
The experiments respecting which the speaker delivered a 
report were instituted in common. From the carotid artery of 
an animal habituated to regular work—a draught dog—were 
taken quantities of blood which sufficed for the purpose of 
analysing the gases of the blood. The quantities of blood 
referred to were taken on one occasion while the dog was ina 
state of rest, lying comfortably at his ease in his cage; 
or on another occasion while the dog was at work pulling a 
loaded car in his usual manner. By an ingenious contrivance, 
which the speaker described, the discharge of blood was ren- 
dered possible without the dog noticing anything of the matter. 
In a similar manner, by special apparatus, without molesting 
the dog in any way, they were enabled to measure the quantity 
of the air breathed in a given time, and to take away small 
quantities of the exhaled air to be subjected to analysis. The 
examination of the blood-gases showed that the arterial blood 
during work contained less carbonic acid and more oxygen than 
it did during a state of rest. During work the blood contained 
about 39 per cent. CO,, and in a state of rest about 40 per cent. ; 
the amount of oxygen, on the other hand, was about 18 per 
cent. during work, and about 12 per cent. in time of rest. The 
respiratory activity was, however, during work considerably 
increased. The quantity of exhaled air during work increased 
to threefold that exhaled in time of rest, and, corresponding with 
the increased respiratory activity, the air exhaled during work 
showed a less increase of CO, and a smaller loss of oxygen than 
in time of rest. The increased respiration during work could 
not now be caused by the blood-gases, seeing that the contents 
of the arterial blood in CO, were less, and in oxygen consider- 
ably more, than during a state of rest. Another stimulus 
must accordingly act on the central organs of respiration 
during work. It was possible to imagine that, along with 
the voluntary excitation of the muscles of the body during work, 
the respiratory muscles might likewise be stimulated, or that 
from the corporeal muscles contracting themselves during work 
a stimulus proceeded reflexively exciting the respiratory centres. 
The following experiment, however, was against both of these 
possible assumptions. The spinal marrow of an animal was in- 
tersected at the top of the thoracic vertebra, and the para- 
lysed lower extremities tetanised while the anterior part of the 
body remained at rest. Notwithstanding, however, that all 
nervous connection between the working muscles and the 
respiratory centre was cut off, the dyspncea of work still 
ensued, and disappeared when the tetanus ceased. From 
this fact the speaker drew the inference that in the active muscle 
some product or other was generated which arrived with the blood 
at the respiratory centre and excited it. The accuracy of this con- 
clusion was further confirmed by the following experiment. The 
abdominal aorta of the animal with intersected spinal marrow 
was, during the tetanus of the posterior extremities, strongly com- 
pressed through the abdominal integuments. The respiration 
now continued unchangedly normal, nor did any dyspnoea ensue 
so long as the compression lasted. Dyspnoea showed itself, how- 
ever, the moment the compression was removed. Even when 
the aorta was left free after the tetanus was ended, increased 
respiration still occurred. The speaker conceived therefore he 
had conclusively established that a substance, still unknown, 
forming itself during the muscular activity, proceeded with the 
blood to the respiratory centre and excited it. He conjectured 
that, in other active organs as well, such an efficient substance 
developed itself as respiratory stimulus, a substance which oper- 
ated along with the gases of the blood even in the normal respira- 
tion. In the discussion following this address, Prof. Zuntz 
mentioned that Dr. Lehmann had made some experiments 
respecting the effect of acids on the respiratory centre, and had 
found that the acids excited this centre. This excitation was of 
course not powerful enough to justify the conclusion that the 
acid produced during the muscular contraction was the respi- 
ratory stimulus in the dyspnoea of work. 
Meteorological Society, April 6.—Prof. von Bezold, the 
newly appointed Director of the Meteorological Institute in 
Prussia, which is to be reorganised, explained the principles in 
accordance with which the reorganisation in question would be 
undertaken. He first gave a short survey of the history of 
meteorological observations, setting forth how, first, the dis- 
ciples of Galileo in the Academia del Cimento made use of the 
newly invented instruments for the observation of temperatures 
and atmospheric pressure ; how, next, as éarly as the beginning 
of the eighteenth century, several investigators of nature had 
arrived at the knowledge that meteorological observations of any 
