Twenty-fib ST Annual Meeting. 101 



162. A, caninum Reich.; Wheat grass. 



163. A. violaceum Beauv.; Wheat grass. 



54. HOBDEUM L. 



a. Awns about 2 inches long, spike bushy in appearance 164 



a. Awns about i-inch long, spike not so bushy 165 



164. Hordeum juhaluin L.: Squirrel-tail grass. 



165. H. pusillum Nutt.; Small Squirrel-tail grass. 



55. Elymus L. 



a. Culms rather tall, 2-5 feet high, outer glumes with short or long awns (6). 



a. Culms about a foot high (seldom 2 ft.), outer glumes long awned 169 



6. More or less pubescent, spike usually slender, awn 1 inch long 168 



6. Plant (except sometimes the flower) not pubescent {a). 



c. Spike rigidly upright, peduncle short, often included in sheath 166 



c. Spike (5-9 in. long) soon nodding, on an exserted peduncle 167 



166. Elymus Virginicus L.; Wild or Smooth Rye grass, Terrell grass. 



167. E. Canadensis L.; Wild Rye, Lyme grass, Terrell grass. 



168. E. striatus Schultz; Rye grass, Dennett grass. 



169. E. Sitanion Schl.; Rye grass. Small Western Rye grass. 



56. ASPEELLA Willd. 

 a. Spike loose, 3-6 inches long, spikelets early deciduous 170 



170. Asprella hystrix Willd.; Bottle-brush grass. 



THE HUMAN EYE: THE CHANGES WHICH OCCUR IN MIDDLE LIFE. 



BY W. D. BIDWELL, A.M., M.D., LEAVENWORTH, KANSAS. 



The following are the changes which occur in the eye in or near middle life, which 

 we will consider briefly: 



First, that condition known as Presbyopia, or the sight of old age. 



Second, Cataract. 



Third, Myopia, or near-sightedness. 



Fourth, Epiphora, or the overflow of tears upon the cheek. 



The condition known as Preisbyopia is due to a change in the consistency of the 

 crystalline lens. In infancy the lens is composed of a somewhat elastic substance? 

 held in position by a membrane known as the suspensory ligament; the posterior 

 surface is more convex than the anterior, but when the suspensory ligament is re- 

 laxed the natural elasticity of the lens causes it to become more convex, particularly 

 anteriorly, bringing the focus nearer the eye and at the same time the iris contracts, 

 shutting out rays which would be rendered too divergent to come to a focus on the 

 retina. In process of time the lens grows larger, heavier and less elastic, so that the 

 focal distance for the eye or the distance of the near-point, as it is called, becomes 

 greater, and when it exceeds ten inches, which is usually between the ages of forty 

 and forty-five years, reading becomes tiresome or impossible, because at the distance 

 at which the book is ordinarily held, the whole accommodation (that is, relaxation 

 of the ligament referred to above) which is available has to be used, and hence fa- 

 tigue is soon experienced; while if the book is held further away only large print 

 can be read, because of the diminution in the size of the retinal images. The rem- 

 edy for this is supplementing the accommodation by convex spectacles of such a 

 strength as to bring the near-point back to nine inches. The hardening of the lens 



