636 A 

(Beth. z. bot. Centibl. 39:19, 1922) that the same 
applies to the chloroplasts and to the xanthophyll 
grains in the petals. Also in the experiments of 
Bottomley (Proc. Roy. Soc. B, 89: 481-507, 1917), 
on the effect of auximones in stimulating the growth 
of Lemna, his figures show (see pl. 22) that not only 
the cells and nuclei but also the chloroplasts are 
conspicuously increased in size. 
In Enothera gigas the gigantism of these structures 
is inherited, while in the Lemna experiments pre- 
sumably it was not. Incidentally, this is an example 
of the same character being inherited in one case and 
notin another. But in its bearing on the fern chloro- 
plasts it is interesting as showing how the cell as a 
whole controls the characters of its contained chloro- 
plasts. The abrupt change from large dark to small 
pale chloroplasts in the fern prothallia seems to be of 
the nature of an “all or none” reaction in the 
genesis of the cell. ; 
That such abrupt transitions do not always occur, 
however, is shown by certain striped varieties of 
maize (Randolph, Bot. Gazette, 73 : 337, 1922) in which 
there is a transition zone where the cells contain 
plastids of-many intermediate sizes and depths of 
colour even within a single cell. 
R. RuGGLes GATEs. 
King’s College, Strand, 
London, W.C.2, 
April 18. 
Nightingale in Uganda. 
ORNITHOLOGISTS may be interested to know that 
in March, when in camp in the part of the Northern 
Province of Uganda known as West Madi, on two 
successive mornings I heard a nightingale singing 
vigorously about 8-9 a.m. : the bird did not commence 
at daybreak, nor did he sing at night. 
From the unfinished character of the song, and the 
lack of fulness and richness of the notes, I suspected 
that the individual was a young bird which had not 
yet fully developed his powers. 
My attention was attracted on March 13, the day 
I reached the camp, about 8.30 a.m., by the familiar 
sound, so different from that of any African bird of 
the locality : unfortunately, I could not see the bird 
in the thick bush. The spot was just such as would 
have been chosen. by a nightingale in England: a 
large clump of big trees with underbush like a small 
copse. 
The camp was Moyo, about twenty miles west of 
the Nile and some ten miles south of the Uganda- 
Sudan frontier. 
I should be glad to know whether nightingales are 
often heard to sing south of the Sahara. I imagine 
that this bird was perhaps making its way northwards 
from its winter quarters. 
G. D. HALE CARPENTER. 
Uganda Medical Service, Khartoum, 
April 23. 

Photography of Balmer Series Lines of High 
Frequency. 
I HAVE recently performed a simple experiment 
with the luminous discharge through hydrogen, 
which has given results of some interest. 
As is well known, it is difficult in the laboratory 
to photograph more than the first few members of 
the Balmer series, although higher members are well 
developed in the stars and nebule. 
Prof. R. W. Wood has shown recently that fifteen 
or twenty of the Balmer lines can be photographed 
in a specially constructed tube running under very 
particular conditions, but Ithave found that an 
NO. 2793, VOL. III] 
NATURE 

[May 12, 1923, 
easy way of securing what appear to be similar — 
results is merely to evacuate the hydrogen tube to © 
a very low point, and then to cause the discharge to — 
pass by the use of a glowing cathode. F 
Under these conditions, the Balmer series is 
brightened relatively to the segondary series ; more- 
over, the brightness of the higher frequency lines is 
enhanced. 1, 5/9 
The experiment is clearly suggested by the atomic 
model of Bohr. 
I hope to publish a detailed account of the investi- 
gation shortly, as I am not aware of any previous 
experimental work along these particular lines. 
R. WHIDDINGTON, 
The University, Leeds, 
April 21. 

Mechanism of the Cochlea. ee, 
I THINK it is evident that Prof. H. E. Roaf (NATURE, 
April 14, p. 498) and I approach the problem of the 
action of the cochlea from different aspects. He 
says: “‘ A variation in pressure applied to the fenestra 
ovalis, if it is to cause a movement of the basilar 
membrane, must cause movement of the liquids in 
the cochlea.’’ Most writers on the cochlea have 
started with this assumption, which is fundamental 
for the theories of Wrightson, Lehmann, Meyer, 
ter Kuile, and Hurst. But it is not possible to 
explain in this manner the fact that sounds can be 
conducted through the bones of the skull, and analysed 
in the cochlea in the same way as air-borne sounds. 
The bone-conducted sounds must be conveyed 
through the cochlea fluids to the basilar membrane 
as waves of condensation and rarefaction in the 
fluid. The impulses thus given to the basilar 
membrane must set swinging the sector of the basilar 
membrane in tune with their frequency. 
impossible for the sector to move without setting in 
movement the fluid columns between the sector and 
the round and oval windows which constitute its 
“load.” Thus, the movement of the cochlea fluid 
originates at the basilar membrane. This phenomenon 
of bone conduction is illustrated quite clearly in my 
model, which gives localised responses at the same 
levels whether the tuning-fork is applied to the 
stapes or to the front or back of the brass case. 
There is no reason to suppose that the case is 
different for air-bornesounds. Wecanstate positively — 
that the waves of sound do produce alternating 
pressure changes in the cochlea fluid, but we cannot 
be certain that any movement of the cochlea fluid 
results from these pressure changes until one or 
more of the sectors of the basilar membrane is set 
swinging. : 
Regarding the action of the cochlea entirely as a 
resonance manifestation, fluid friction counts only — 
as a damping factor. It has important bearing on 
sharpness of resonance and persistence of vibration, — 
but its magnitude is very difficult to estimate. ; 
I am afraid I do not quite follow Prof. Roaf’s” 
suggestion as to the spiral ligament. He says “ the 
greater bulk of the spiral ligament [in the basal coil] 
may be merely to resist a greater strain.’’ Does 
Tt sae 
P 
¢ 
4 

7 
mean bending strain or breaking strain? If .., 
ee 
former, the only way in which it could so act woulc 
be by producing increased tension, as I (following — 
Gray) have supposed. If the latter, the bee 
strain of the basilar membrane would be determine 
by the strength of its weakest part. However — 
strong the spiral ligament might be, it could not 
prevent the basilar membrane being torn if excessive _ 
force were applied to it. GEORGE WILKINSON. 
387 Glossop Road, Sheffield. 
. 
