SIGHT. 585 



his respiratory set and are for expression, and that the two oblique 

 muscles have the same destination, and are not voluntary ; while 

 the four recti muscles and their common motor and abducent 

 pairs of nerves are voluntary. Now, in the first place, all the 

 objections that I formerly made to his views of a respiratory set 

 of nerves for expression (p. 459. sqq. supra] hold good in the 

 present case, which is merely a particular instance of those views. 

 The absurdity of applying the term respiratory to nerves and 

 muscles of the eye is too manifest to require comment. In the 

 next place, he conceives that the two oblique muscles are never 

 voluntary ; and he contends that the superior draws the pupil 

 downwards and outwards, the inferior upwards and inwards. 

 Other writers d say downwards and inwards, and upwards and 

 outwards ; but he agrees with all, that their combined action 

 draws the eye towards the nose, though I hardly understand 

 how, on either supposition, such a motion inwards can result. 

 Now, we can move the eyes downwards and outwards, and up- 

 wards and inwards, at pleasure : we can also make them approach 

 each other at pleasure, and it is a mere assumption, and a very 

 improbable assumption, that we do this by the internal straight 

 muscles, and not by the combined action of the two obliques. 

 He mentions experiments in which he divided the superior oblique, 

 and another in which he divided the inferior oblique ; and he asserts 

 that the voluntary motions were unaffected. The poor animal no 

 doubt moved its eye upwards and downwards, inwards and outwards, 

 as it had four muscles left for these purposes : but we, of course, 

 have no information given us that an attempt was made to in- 

 duce the animal to approximate both eyes together, as in looking 

 now at a distant and now at a near object in the same line ; and 

 this I believe to be the use of the oblique muscles, just as it is 

 of the straight to act when we look in different directions. He 

 divided the superior oblique of the right eye, held open the 

 eyes, waved the hand before them, and found the right eye 

 move upwards and inwards, and the other scarcely so in that 

 direction, and the dog " seemed to have a difficulty in bringing 

 it down again." But this did not show that the muscle was 

 involuntary. If the superior oblique moves the eye downwards 

 and outwards, its division explained, on his own views of the 

 effects of these mnscles, why the animal could not move the eye 



d Manuel d' Anatomic comparee, par Jules Cloquet, p. 139. sq. 



