470 Litelligence and Miscellatieoiis Articles. 



or by enematas, and, if necessary, he would consider the injection of 

 water into the veins a feasible experiment. He proposes that in these 

 instances, the water should hold in solution a proper proportion of 

 those saline matters which naturally exist in the blood, as these prin- 

 ciples also are diminished in the diseased fluid. — Dublin Journal of 

 Medical and Chemical Science, No. II. p. 213 — 215. 



Dr. Thomson's Analysis of the Blood of Cholera Patients will be 

 found in our last Number, p. 347. 



MR. Mackenzie's observations on glaucoma. 



This affection of the organ of vision is scarcely less interesting in 

 a physical than in a pathological point of view ; in fact, the eye in 

 glaucoma suffers more as a camera obscura than as a sentient organ. 



The term glaucoma (from yXdvyco;, green or blue, the colour of the 

 sea) appears to have been applied by Hippocrates to every sort of 

 opacity situated in the interior of the eye. Rufus and his successors 

 limited its meaning to opacity of the crystalline lens ; and presuming 

 that the lens was the immediate organ of vision, concluded that such 

 opacity was necessarily a cause of irremediable blindness. One sort 

 of opacity, situated behind the pupil, they knew to be curable by 

 couching; and on this sort they bestowed the name of hypochysis, on 

 the supposition that it consisted in an efl'usion of new or morbid mat- 

 ter between the pupil and the crystalline lens. Cataract is a still more 

 modern term, and for a time was used synonymously with hypochysis. 

 It was only about the beginning of the last century that the notion of 

 the ancients, that cataract was in all instances an effused substance, 

 was refuted by the observations and dissections of Maitre-Jan and 

 others, who showed that in common cataract it is the lens itself which 

 becomes opake. At the same time, as morbid effusions actually take 

 place in certain cases between the pupil and the lens, a distinction arose 

 between true and spurious cataract) the true having its seat in or within 

 the crystalline capsule, and the spurious without. Brisseau, in dis- 

 secting the eyes of Bourdelot, physician to Louis XIV., was led to 

 believe that, besides the opacities now mentioned, another occasion- 

 ally occurred behind the lens, or in the vitreous humour ; and to this 

 deep-seated opacity he proposed to apply the term Glaucoma. This 

 acceptation has accordingly been generally received. A deep-seated 

 opacity in the eye, of a greenish colour, is a frequent occurrence, 

 especially in advanced age, attended with preternatural hardness of 

 the eye, and more or le-ss defect of vision. These are the signs of 

 glaucoma, and have till very latelr been attributed to an opake and 

 inspissated state of the vitreous humour. 



Mr. Mackenzie of Glasgow has lately explained the true nature of 

 glaucoma. His dissections of glaacomatous eyes show that the vi- 

 treous humour, so far from being opake in glaucoma, is perfectly 

 pellucid, and so far from being inspissated, is actually dissolved. The 

 watery fluid which occupies the pUce of the vitreous humour is of a 

 yellowish hue, and from its supera))undant quantity distends the tu- 

 nics of the eye more than the viicous humour does in its natural 

 state, so as to produce an unnatural firmness of the eye. The other 

 changes, observed by Mr. Mackenzie, refer to the choroid coat, retina, 



and 



