430 
iNATURE 
[MaRcH 3, 1904 
difference formula, are, up to a temperature of rooo° C., 
in close agreement with the results obtained from the con- 
stant volume nitrogen thermometer, employing chemical 
nitrogen, and using the received value for the dilatation 
of the Berlin porcelain, of which the bulb is made. 
(2) The platinum thermometers agree very closely with 
a set of thermo-junctions representing the temperature 
scale of the Reichsanstalt, based on measurements with a 
gas thermometer haying a bulb of platinum-iridium. 
As the results of these experiments seem to justify very 
completely the use of Callendar’s parabolic formula over 
a wide range, a table has been calculated by which the 
value of IT may be obtained directly from the value of 1 
for a range of temperature extending from —200°-1100° C., 
and for the value 1-5 of the constant 6. 
““\ New Method of Detecting Electrical Oscillations.” 
By J. A. Ewing, LL.D., i°.R.S., and L. H. Walter. 
The paper describes a detector of electrical oscillations 
suitable for wireless telegraphy. It is based on Ewing’s 
hysteresis tester, and employs the change which electrical 
oscillations produce in the hysteresis of a magnetic metal 
exposed to reversals of magnetism by means of a revolving 
field. The hysteresis causes the magnetic metal to be 
dragged after the field, and this drag is opposed by a spring, 
a definite deflection of the metal being thereby produced. 
When the oscillations act this deflection undergces a sudden 
change which constitutes the indication. 
Under the conditions first experimented on, the authors 
found, as they expected, a reduction of the hysteresis de- 
flection when the oscillations acted. But in later experi- 
ments, when the magnetic metal was arranged in the form 
of a fine insulated steel wire through which the electrical 
oscillations were caused to pass, it was found that they 
produced a large increase in the deflection. 
In the instrument exhibited the revolving field is supplied 
by an electromagnet with long wedge-shaped pole pieces 
between which a long bobbin of the steel wire is pivoted, so 
that the magnetic drag tends to make it turn on its axis. 
It is controlled by a spring and furnished with a mirror 
or other indicator of deflection. The bobbin is wound with 
about 500 turns of No. 46 gauge hard-drawn steel wire, in- 
sulated with sill, the winding being non-inductive. It is 
immersed in oil, which serves to steady the deflection as 
well as to reinforce the insulation. 
The detector gives quantitative readings, and, in some 
cases, the deflection may be too large to be easily read by 
the scale. For this purpose a variable shunt is provided, by 
which the deflection can be regulated. 
For the purpose of wireless telegraphy, the instrument 
has the advantage of giving metrical effects. The benefit 
of this in facilitating tuning, and in other respects, need 
not be insisted upon. 
From the physical point of view, the augmentation of 
hysteresis is interesting and unlooked for. It is probably 
to be ascribed to this, that the oscillatory circular magnet- 
isation facilitates the longitudinal magnetising process, en- 
abling the steel to take up a much larger magnetisation 
at each reversal than it would otherwise take, and thus 
indirectly augmenting the hysteresis to such an extent that 
the direct influence of the oscillations in reducing it is 
overpowered. The net result appears to be dependent on 
two antagonistic influences, and, in fine steel wire, under 
the conditions of the experiments, the influence making for 
increased hysteresis, as a result of the increased range of 
magnetic induction, is much the more powerful. 
Linnean Society, February 4.—Prof. S. H. Vines, F.R.S., 
president, in the chair—Mr. C. E. Salmon exhibited two 
specimens of Epilobium collinum, C. C. Gmel., from Scot- 
land, with a series of FE. montanum and E. lanceolatum for 
comparison.—The President gave an account of re- 
searches into the physiology of the yeast-plant (Saccharo- 
myces Cerevisiae). He directed attention to the fact 
that though this plant consists of but a_ single 
minute cell it produces a variety of enzymes or ferments: 
diastase, invertase, zymase, as well as an 
undefined enzyme, protease, which digests proteid matter. 
The proteolytic activity of yeast has engaged the attention 
of many observers, of whom Hahn and Geret express the 
opinion that the plant contains a protease which resembles, 
NO. 1792, VOL. 69] 
glucase, 
in some respects, the pepsin of the animal body, in other 
respects the trypsin. In November, 1902, the discovery of a 
protease resembling the recently discovered erepsin of the 
animal body was announced by the president. Since then 
he has endeavoured to determine whether or not the proteo- 
lytic phenomena of yeast may not be due in part to the 
presence of an enzyme of this character, with results which 
indicate that this is the case. A filtered watery extract of 
yeast readily decomposes the simpler proteids, such as 
albumoses and peptones, into non-proteid bodies, such as 
leucin, tyrosin, &c., as indicated by the tryptophane-reaction. 
Such an extract was, however, in no case observed to exert 
any digestive action upon a higher proteid, such as fibrin. 
The conclusion to be drawn is that the protease extractable 
from yeast by water is an erepsin. Yeast contains a 
protease that digests fibrin. If yeast be extracted with a 
2 per cent. solution of common salt, a liquid is obtained 
which digests fibrin with certainty. What, now, is the 
nature of this protease that digests fibrin? Though the 
point can only be finally settled by separating and isolating 
the two proteases, the probability is that this peptonising 
enzyme is a vegetable trypsin. The conclusion suggested 
by the observed facts is that yeast contains at any rate two 
proteases, the one an erepsin, the other probably a trypsin. 
—Mr. E. S. Salmon gave an account of his further re- 
searches on the specialisation of parasitism in the 
Erysiphaceee. The comparative inoculation experiments of 
1650 leaves of various species of Bromus, carried out by the 
author, have shown that a very high degree of specialisa- 
tion has been reached in the adaptive parasitism of Erystphe 
Graminis, DC., to the different species of the genus Bromus. 
This specialisation has involved the evolution of a consider- 
able number of ‘‘ biologic forms ’’ of the fungus. The facts 
obtained show not only the high degree of specialisation 
which the fungus has undergone, but also that each species 
of Bromus possesses distinctive physiological characters 
existing concomitantly with the specific morphological 
characters. 
Physical Society, Feb. 12.—Annual general meeting.— 
Dr. R. T. Glazebrook, F.R.S., president, in the chair. 
The president delivered an address in which he dealt with 
one or two matters connected with the theory of the micro- 
scope. 
EDINBURGH. 
Royal Society, January 4.—Prof. Duns in the chair. 
—In a paper on the bilateral origin of the epiphysis in the 
chick, Dr. John Cameron showed that the epiphysis in 
the chick arises in the form of two bilateral outgrowths, of 
which the left is by far the better marked of the two. 
These results correspond in their main features with those 
already obtained by the author in the case of the Amphibia. 
The evidence is gaining ground that the epiphysis is 
bilateral and not mesial in origin——Prof. A. C. Mitchell 
gave an account of a multi-metre resistance bridge, which 
he had constructed for investigations in which very strong 
currents were to be used. There were some special features 
for securing steady pressure contact. The many standard 
coils which could be arranged in a great variety of ways 
were loosely wound in long coils, and the temperature was 
determined by the change of resistance of a platinum coil 
wound similarly in the heart of the collection of resistance 
coils. The coils were made of Beacon wire, and had all 
been carefully standardised by the Board of Trade.—Two 
mathematical papers by the Rev. F. H. Jackson dealt with 
certain fundamental power series and their differential 
equations, and an additional note on generalised functions 
of Bessel and Legendre. 
January 18.—Dr. Robert Munro in the chair.—Prof. 
Graham Kerr read a paper on the early development of 
motor nerves and myotomes in Lepidosirven paradoxa, Fitz. 
Photographs taken from untouched negatives were shown 
illustrating the following points:—(1) the fact that the 
motor nerve trunks existed as metamerically repeated 
bridges of granular protoplasm at a period when myotome 
and spinal cord were still in contact; (2) that the nerve 
trunk was at first naked; (3) that later on it received a 
covering of yolk-laden mesenchymatous protoplasm which 
spread itself out and formed a continuous protoplasmic 
sheath; ‘and (4) that at certain stages complete continuity 
