814 



PHYSIOLOGY. 



solidity or depth, since experience has taught us that those objects 

 only which have depth can affect the eyes in this way. 



The photographs are slightly different from each other, for if 

 they were identical no sensation of relief will ensue. The combina- 

 tion of the dissimilar images furnished by the two eyes is a mental 



act. 



o 



Fig. 366. Direct Ophthalmoscopy. (BALL.) 



Lacrymal Secretion. Lately it has been shown by Landolt that 

 in the rabbit and the monkey secretory nerves of the lacrymal gland 

 run in the facial nerve. These nerves leave the geniculate ganglion 



O 



Eve Lens 



Fig. 367. Indirect Ophthalmoscopy. (BALL.) 



and enter the superficial petrosal. We then find them in the supe- 

 rior maxillary and occasionally in the ophthalmic. He believes these 

 fibers run in the glosso-pharyngeal and then in the facial, but he did 

 not locate the nucleus from which they arise. Eserin increases the 

 secretion of tears, atropine decreases it. 



