TRANSACTIONS OF THE SECTIONS. 171 



cles used as food in the prisons of Bengal was given on the authority of the analysis 

 propounded by Dr. Forbes Watson, and four different scales of diet were recom- 

 mended : 1, for Bengalese and Assamese ; 2, for natives of Behar, the North-west 

 Provinces, and the Pimjab ; 3, for Coles, Sontals, GaiTows, and Hillmen generally; 

 and 4, for Mughs and Chinamen. The last-named were fond of cats, dogs, rats, or 

 any animal food, and mere vegetable diet never satisfied them. The scales referred 

 to were all for long-term convicts, and were stated to be the minimum to maintain 

 health and strength. 



On the Existence and Arrangement of tlie Fovea Centralis Eetince in the Eyes 

 of Animals. By Prof. H. Mullee. 

 The fovea centralis and macula lutea have generally been regarded as a peculiarity 

 of man and qufidrumana. The physiological dignity of the spot, and the power to 



see an object at the same time with the two fovese, seemed to secm-e to the organ 

 of vision of these beings an exceptionally high position. But this is not true. I can 

 say, for the moment, that the chameleon and at least many birds which possess the 

 apparatus for optic accommodation so highly developed are also endowed with the 

 delicate nervous apparatus represented by the fovea and the thicker parts surround- 

 ing it. The extent of siu-face which presents this peculiar organization is found 

 sometimes so great, that a very considerable part of the retina may be compared to 

 the macula lutea of the human eye. There is in this part of the retina of these 

 animals the peculiar arrangement of the bimdles of nerves, which ai'e ciuved roimd, 

 so that many fibres come into, but none pass over it. There is the accumulation 

 of ganglion-cells, which form several layers in the circumference of the fovea. 

 There is the peculiar conformation of the external layer of the retina, in which the 

 elements sensible to light are thinner and longer than elsewhere ; so that in the 

 fovea this layer, necessary for the first reception of light, alone is thicker, while 

 the other layers are attenuated. There is, finally, the oblique course of the fibres 

 in the granular layer, which put in communication the enormous quantity of sen- 

 sible elements in and next the fovea with the ganglion-cells in the neighboiu'hood. 

 It is at the same tune very interesting, that the two species of radial fibres in the 

 retina of which I treated ('On the Retina,' 1856, p. 72), namely, of nervous and 

 connective tissue, have in those animals a different course— in the granidar layer 

 the one sort running obliquely, the others rimning perpendicularly to the external 

 surface of the granular laj^er. The fovea centralis is ordinarily to be found in the 

 eyes of bii'ds next to the posterior pole of the sclerotica, but sometimes excentri- 

 cally therefi'om towards the temporal part of the eyeball. In owls the excentricity 

 is so great, that a common act of vision in the two fovese is very reconcileable with 

 the position of the eyes in these animals. In some mammalia, besides quadrumana, 

 there exists at least an area centralis which approaches the an-angement of the 

 yellow spot ; the course of the vasa centralia, wanting in birds, at the same time 

 becomes more like the human eye." 



On the Influence of the Sympathetic Nerve on Voluntary Muscles, as witnessed 

 in the Treatment of Progressive Muscular Atrojihy by Secondary Electric 

 Currents. By Professor Eemak. 



Physiological Researches on the Artificial Production of Cataract. 

 By B. W. EiCHAEDSON, M.D., M.A. 

 In the course of his remarks the author said that syrup of sugar injected into the 

 circulation of a frog would produce cataract, and he exhibited a nimiber of living 

 frogs in which he had produced the disease by this means. The same injection 

 produced the same result on both guinea-pigs and rabbits. An injection of com- 

 mon salt also acted like sugar, the only difference being that it produced harder 

 cataract. If any of the soluble salts of the blood were present in excess, they 

 would produce this condition. In 1838, at a meeting of that Society, Sir David 

 Brewster had said that cataract was caused by the disan-angemeut of the fibres of 

 the lens of the eye, and his theoretical notion had now turned out to be quite cor- 

 rect. In reply to a number of questions put to him, Dr. Richai'dsou said that the. 



