TRANSACTIONS OF THE SECTIONS, 121 
corresponding points of the two retine might continue on the same level 
when the head was inclined to either side. Dr. Ashe considered that this effect 
could only be produced with reference to a single pair of points in the retine at 
any one moment, and that only at the expense of an increased alteration in the 
level of every other pair of corresponding points. But he considered the attain- 
ment of this object unnecessary, inasmuch as any corresponding pair of points 
changed their level only with reference to the level of the earth’s surface, and not 
with reference to the point looked at; this point, therefore, with the two on the 
retinze, would remain in the same relative position notwithstanding the rotation of 
the plane containing them. Hence Dr. ithe considered that the function of these 
muscles was yet to be assigned; while, on the other hand, a known function existed, 
capable of being voluntarily discharged, for the exercise of which no voluntary 
muscle had been assigned, namely, the adjustment of the focal distance of the eye. 
It had been considered that the ciliary muscle effected this by compressing the 
globe. No doubt the action of the ciliary muscle might cause short-sightedness, 
and this defect had vecently been remedied by its division ; but the ciliary muscle 
consisted of unstriped fibres, and its action must therefore be involuntary, which 
was also demonstrated by the fact that the power of voluntary adjustment of the focal 
distance was not destroyed by its division. Dr. Ashe considered that the position 
of the obliqui was such that, acting together, and not separately as generally sup- 
posed, they would compress the globe of the eye, as the ciliary muscle might do 
involuntarily, and thus increase its refractive power by augmenting the antero- 
posterior axis. A diminution of focal distance would hence result. The retina 
would be thrown backwards by the same action, and its power of receiving a dis- 
tinct image from a near object enhanced considerably thereby. The elasticity of 
the sclerotic coat would increase the focal distance again on the cessation of the 
voluntary action of these muscles. This view was confirmed by the fact that a 
person was conscious of a voluntary effort in adjusting the sight to an object placed 
very near the eye, much more so than he would be to any effort in looking at a 
distant object. It had been supposed that the four recti muscles, acting together, 
might compress the globe and cause a shortening of the focal distance ; Dr. Ashe con- 
sidered that the only effect of such a cooperation would be to draw the eyeball 
back into the orbit, and, if anything, rather diminish the antero-posterior diameter 
of the globe; certainly they could not increase it unless they had osseous attach- 
ments anteriorly as well as posteriorly. But it had been demonstrated that the 
muscular fibres of the obliqui were continuous quite round the eyeball; and hence 
if they were to act together, as Dr. Ashe suggested, their effect would undoubtedly 
be to increase the antero-posterior diameter of the globe. To correspond with such 
a diminishing of the focal distance a slight approximation of the antero-posterior 
axes of the eyeballs would be necessary, and were this to be accomplished by the 
same mechanism the requisite correlation would be established between the two 
actions. This would be effected by the muscles in question if the point where their 
actions balanced each other were placed a very little anterior to that circumference 
of the eyeball which should pass through their fixed.attachments, and this Dr. Ashe 
considered was exactly the position of their insertion into the sclerotic. 
On voluntarily shortening the focal distance the pupil might be observed to con- 
tract, relaxing again when the focal distance was elongated; this seemed to cor- 
roborate Dr. Ashe’s views, since the inferior obliquus and the circular fibres of the 
iris were both supplied by the third nerve, and might be simultaneously affected by 
its action. 
In experimenting on the dead body, Dr. Ashe had found that, by the sense of 
touch, a distinct elongation of the antero-posterior axis of the eyeball could be 
recognized on drawing at once on the two obliqui; he had found the sense of touch 
the most delicate indication of the alteration. 
On the Scientific Cultivation of Salmon Fisheries, 
By Tuomas Asnworru, of Cheadle. 
The main objects of this paper were to show the great value of salmon-fisheries, 
how they have been neglected in England, and how they might he improved, The 
