TWENTY-FIBST ANNUAL MEETING. 103 



Before leaving the subject of cataract, I will just mention one fact that is fre- 

 quently misleading. In commencing cataract, the refractive power of the nucleus 

 of the lens may be increased so that one who had been compelled to wear convex 

 glasses for presbyopia is enabled to leave them off: hence, they imagine their sight is 

 improving with age, whereas it is on the road to a more rapid failure. 



Having referred to hypermetropia, or far-sightedness, in connection with pres- 

 byopia, it would not be quite fair to entirely ignore the opposite condition of my- 

 opia, or near-sightedness, as it is called. Myopia is usually due to a lengthening of 

 the globe of the eye, as a result of weakness of the tunics. It may be congenital, 

 but more often comes on during childhood. The employment of the eyes, in child- 

 hood, for near work, with a defective light, the head being bent over, will make the 

 trouble much worse, if, indeed, it is not sufficient to originate myopia. A feeble 

 condition of the system tends to increase the trouble, and in many cases the vitreous 

 finally becomes fluid, and opacities are seen in it and in the lens. With proper care, 

 the disease progresses but slowly in the majority of cases; but with abuse of the eye, 

 stronger glasses are required at frequent intervals, and the vision becomes very 

 feeble. The remedy consists in wearing a proper glass, and in avoiding the causes 

 already mentioned. 



The only other disease I will refer to at this time is Epiphora, or the overflow of 

 tears upon the cheek. Normally the tears are discharged through several small 

 canals coming from the lachrymal sac in the upper and outer corner of the orbit, 

 over the front of the eye, and are taken up through two minute orifices, called the 

 puncta lachrymalia, situated one in the upper and one in the lower lid at the inner 

 angle of the orbit. These two open into canaliculi, which unite and form the lach- 

 rymal sac, and this in turn opens into the nasal duct discharging the tears into the 

 nose. The orbicularis muscle, which closes the lids, sharing in the general diminu- 

 tion of vitality of the system, may become relaxed, and the puncta are then no 

 longer applied to the surface of the globe, but point outward, and allow the tears to 

 escape upon the cheek, giving rise to inflammation of the skin, and the unsightly 

 appearance noticeable in many aged people. These cases are sometimes entirely 

 relieved by the simple operation of opening up the canaliculi so that the tears are 

 readily received into the sac; but others are only relieved by dilating the whole nasal 

 duct, which evinces a decided inclination to close up if irritated by acrid discharges 

 from the eye. 



AN EXAMINATION OF THE EESINOUS EXUDATION OF KOSIN WEED. 



[Silphium Laciniatium.) 



BY PROFESSOR L. E. SAYRE. 

 (Abstract.) 



The rosin weed exudes a resinous juice, which congeals in small transparent or 

 translucent masses or tears. This resin is quite beautiful and interesting, and, it 

 seemed to me, could be made of value in making a fluid for use in microscopic 

 mounting. 



On examination, this deposit proved to be quite a pure oleo-resin. It is soluble 

 in chloroform, benzol, ether, and benzine. Alcohol and methyl alcohol dissolve it to 

 some extent. The chloroform and benzol solutions are perhaps the best for micro- 

 scopic purposes. They leave, upon spontaneous evaporation, a transparent residue. 

 If the solution is evaporated, and the heat continued until the volatile oil is driven 

 off, the residue makes a solution in benzol or chloroform which dries very rapidly 

 into a thin, transparent film, which is well adapted to microscopic mounting. 



