232 JOURNAL OF SCIENCE. 
and growth, and very susceptible to outer influences, the effects 
of which easily became settled and permanent. When children 
looked persistently at near and small objects, an undue pressure 
on the eye was produced by the accommodation muscle, as well 
as by the accumulation of blood caused by the stooping position so 
often assumed by children. The result of this was that the young 
scholar not only remained short-sighted, but the defects increased 
in proportion to the continuance of injurious influences. Short- 
sighted eyes should not only be guarded against overstraining, 
especially against evening work, but proper counter-influences 
against the prime causes should be instituted—such as practising 
the sight upon distant objects, by much out-door exercise, by 
school gymnastics, and by carefully guarding against that which 
is obnoxious to a normal development of the organ. In order to 
stem the tide of short-sightedness, Professor Cohn made the fol- 
lowing demands to the schools throughout the world—demands to 
which he (Dr. Schwarzbach) fully assented. For the protection ~~ 
of the eyes and sight of school children, it was necessary—(1) To | 
; 
: 
: 
have a pause of fifteen minutes after every lesson of three-quarters - 
ofan hour; (2) to pause half an hour at 11 o’clock if the morning 
instructions are carried on during five hours; (3) to shorten the 
lessons and the tasks at home; (4) to have a reading board for 
testing the sight fixed in the room (if certain letters could not be 
distinguished at a certain distance, the pupil must rest the organ) ; 
(5) to introduce lessons on hygiene in all schools, colleges, and 
universities ; (6) every council of education should have a medical 
man as a member; (7) to close by law all school-rooms which are ~ 
badly lighted and insufficiently ventilated. It was true that short- 
sightedness was often hereditary, but this must not be thought to 
mean that the children of short-sighted parents were born short- 
sighted; they had only the predisposition to become so. Dr. 
Schwarzbach condemned the use of small print in school books, : 
and the existing internal arrangements in schools, which, he said, 
were too often made without sufficient regard tothe proper supply 
of light. + 
PHILOSOPHICAL INSTITUTE ‘OF CANTERBURY 
Christchurch, 6th July, 1882.—Prof. F. W. Hutton, vice- 
president, in the chair. 
Papers—(1) ‘“‘On some points of difference between the 
English Crayfish (Astacus fluviatilis) and a New Zealand one 
(Pavanephrops setosus), by Charles Chilton, M.A. 
In this paper the structure of Pavanephrops setosus was described 
and compared with that of Astacus fluviatilis as described by Pro- 
fessor Huxley in ‘The Crayfish.” The specimens used for © 
dissection were obtained from the River Avon, Christchurch. ~ 
The various appendages were all fully described and figured, as 
well as the rostrum and the tetson. The respiratory organs are 
very different from those of Astacus, but nearly like those of Asia. 
copsis and Palinuvus. The circulatory and alimentary systems 
closely resemble those of Astacus ; but the Gastroliths or ‘‘ Crab’s ~ 
Eyes” of Pavanephrops do not appear to develop in the same way 
as those of Astacus. The nervous system is also much like that of — 
Astacus, except that each joint of the exopodite of the antennule 
es. P j 
has ee oe 
= | 
