May 30, 1912] 
NATURE 
33! 
to recent genera, authors run considerable risk of 
misleading students who fail to appreciate the slender 
grounds on which such supposed affinity rests. 
The volume issued by the Johns Hopkins Press is 
the best account of the Potomac flora so far produced, 
and the careful work of Mr. Berry, who is responsible 
for the greater share of the monograph, is deserving 
of warm praise. A. C. Sewarp. 
THE LUMINOUS ORGANS OF CERTAIN 
INSECTS, 
[X 
The Canadian Entomologist (1911, p. 399), Mr. 
F. A. Macdermott describes a number of 
interesting observations which afford strong con- 
firmation of the view that the photogenic function in 
the Photinini is primarily a secondary sexual 
character; in at least four species in two of the 
genera, Lecontea and Photinus, the photogenic func- 
tion serves undoubtedly as a mating adaptation. 
Direct observation showed that the female of, for 
example, Photinus pyralis responded by an answer- 
ing flash to the flash of the flying male, which then 
dropped down, flashed again, and after her second 
answer alighted a few inches away from her, crawled 
towards her, flashing at intervals—to each of which 
flashes she responded—and finally located her. 
It is interesting that in many cases it was possible 
to deceive the females in an open field by igniting a 
safety match and swinging it in an arc, so as to 
imitate the dipping flight and flash of the male 
pyralis. In each instance the flash of light from the 
match was answered within two to five seconds by 
the flashes ol females of pyralis in the surrounding 
grass and weeds. By the use of a very small electric 
lamp it was found quite as easy to deceive the male 
pyralis. When a male fiashed within about 2 or 
3 ft. of the lamp, the circuit was closed two or three 
seconds afterwards by means of a push-button, so as 
to imitate as nearly as possible the intensity and time 
of flash of the female. : 
No definite instance was observed of a flying male 
mistaking the flash of a creeping male for that of a 
female and dropping to it. Observation on a single 
female of pyralis showed that she would not respond 
to the flash of a female Photuris pennsylvanica, Deg., 
made to flash above her, nor to a male of Photinus 
consanguineus, Lec., although the same _ female 
readily responded to a match. In the case of con- 
sanguineus, the female would answer a double flash 
of the lamp while some 20 or 30 ft. away, but on 
close approach seemed to recognise the difference and 
ceased to respond.  Scintillans female also responds 
to the flash of the male consanguineus flying above 
her, but the latter appears to pay no attention to 
her. 
In a second paper, in the Journal of the Amer- 
ican Chemical Society (vol. xxxiii., p. 1791), Mr. 
McDermott deals with the chemical nature of the 
photogenic material, and shows that if the luminous 
organs of Photinus be dried in vacuo with a residual 
atmosphere of hydrogen, the tissue will retain its 
photogenic power and exhibit it when moistened 
eighteen months after preparation. If the dried 
tissue be moistened with 3 per cent. hydrogen 
peroxide a brighter light is produced than if water 
alone is used and the hydrogen peroxide is actively 
decomposed. If air is admitted to the sealed tubes 
containing the dried organs they rapidly lose their 
photogenic activity. When a living lampyrid was 
dropped into a test-tube immersed in liquid air it 
flashed rapidly for a few seconds, then fell back into 
the tube frozen stiff; meanwhile, the photogenic organ 
began to shine brilliantly, but the brilliancy rapidly 
NO. 2222, VOL. 89| 
| 
| put forward that it is 
diminished, the diminution being accompanied by a 
change in the colour of the light, which became 
reddish. The light finally disappeared, or very nearly 
so, but on warming to the room temperature it re- 
appeared The insect was dead, but the tissue con- 
tinued to glow for some time. 
The probable chemical nature of the photogenic 
substance is discussed, and although there is very 
little real evidence as to its nature, the hypothesis is 
probably an albuminous lipoid 
(phosphatide) which fairly readily undergoes oxida- 
tion. 
NATIONAL TEACHING OF SCIENCE 
SUBJECTS. 
1 consequence of the issue by the Board of Educa- 
tion of Circular No. 776, which abolished 
examinations in the biological sciences, without pro- 
viding any alternative scheme, the Physiological 
Society recently sent to the Board a memorandum 
directing attention to this action as a step gravely 
affecting national education in science. It was 
pointed out by the society that the cessation of the 
examinations in question, by withdrawing central 
guidance and inspiration, rendered it probable that 
unprofitable, inaccurate, and trivial courses of lessons 
would be given, and that in many cases it will lead 
to the abandonment of instruction in biological sub- 
jects in small centres. Moreover, it was insisted 
upon that development of the national teaching of 
science subjects, including biological subjects, necessi- 
tated an inquiry into the reorganisation of education 
in physics and chemistry. 
With regard to the training of teachers, the 
memorandum dealt with the indispensable necessity 
of physics and chemistry as preliminary to physiology 
and with this science in turn as necessary for the 
rational understanding of hygiene, a subject which is 
already a part of the teacher’s training, although no 
adequate provision for training in the necessary 
fundamental preliminary sciences is made. ; 
Further, attention was directed to the fact that no 
teacher can possess a correct appreciation of psycho- 
logy, or its application to national health and educa- 
tion, unless its study has been founded on a basis of 
physiology. 
The Physiological Society, therefore, suggested to 
the Board of Education the desirability of suspending 
the operation of Circular No. 776 in order that re- 
consideration of its effects may be made by the Board, 
and especially directed attention to the necessity of 
reform in the scientific education of teachers and of 
the continuation of (reformed) examination in bio- 
logical subjects (especially in physiology and hygiene) 
until a better method of ensuring adequate training 
in these sciences is established. 
In forwarding this memorandum, the society re- 
quested that a deputation of its members should be 
received by the Board of Education. Accordingly, 
the President of the Board agreed to receive such a 
deputation on May 16. This deputation consisted of 
Sir Victor Horsley, Prof. Sherrington, Dr. Edkins, 
Prof. Starling, Dr. Waller, Dr. Myers, and Prof. 
Bayliss (hon. sec. of the society), and was introduced 
by Dr. Addison, M.P. 
Sir Victor Horsley spoke chiefly on the absolute 
necessity of physics and chemistry as preliminary to 
hygiene. The training colleges were not teaching 
science in this way, but were beginning with bio- 
logical nature-study. The training in science should 
be given to all teachers, and by them in turn to their 
pupils in the elementary schools. 
Prof. Sherrington, who has had much experience 
