ANATOMICAL CONSIDERATIONS. 31 



level waste of shining sand ; or, in other words, the first parents of the 

 tribe must have careered across some burning desert. 



IHE PUPIL OF THE HORSE'S EYE IN THE OPPOSITE STATES OF CONTEACTION AND DILATATION, SHOWING THE 

 SITUATIOK AND THE USE OF THE CORPORA NIGRA. 



The corpora nigra, in the eye of the camel, are black bodies, pendent 

 from the margin of the iris. The purpose of so special a provision is not 

 apparent, when darkness occasions the opening to dilate ; but when the 

 glare is powerful — so powerful as to induce blindness even in the natives 

 of those lands where a concentrated light is possible — then the intent of 

 its Beneficent Creator becomes apparent. 



The pupil of the horse's eye is never circular, being, when much 

 dilated, rather oblong in figure ; but, when exposed to the direct rays of 

 the summer's sun, the' opening energetically contracts. Then the pupil 

 is best represented by a mere line ; for the edges of the iris at such a 

 season seemingly touch each other. In this condition, the uses of the 

 corpora nigra can hardly be mistaken : the little black bodies appear to 

 fit into one another, forming apparently an impenetrable network opposed 

 to the entrance of too strong a glare. 



Let the author and the reader, however, temperately consider this 

 matter. The pupil in the eye of the horse is not more distant than two 

 inches from the origin of the optic nerve. When the division to be seen 

 through is so close, and the object to be viewed is exhibited under the 

 strongest natural light, the merest crevice will be equal to all the pur 

 poses of perfect vision. The full glare of the sun alone occasioning the 

 horse's pupil to contract, that which causes the opening to almost shut 

 also provides the excess of light, which alone could render useful that 

 narrow division through which objects must be recognized; while the 

 dark bodies, being stationed before ithe point of sight, answer the pur- 

 pose of the smoke which lads load upon glass when they are ambitious 

 of gazing at the sun. 



The reader must have remarked the pupillary line through which the 

 domestic cat exercises perfect vision during the bright noon of a mid- 

 summer day. The eye of the feline race is, however, possessed of no 

 Other protection. The contraction may be the effect of weakness of 



