AND ANIMAL LIFE. 213 



ani, the peristaltic action of the intestines and 

 stomach, the elevation of the ribs, or the inor- 

 dinate action of any of the muscles belonging to 

 respiration, in fine, every motion or contraction 

 of muscular fibre, I regard as depending on ner- 

 vous fibrillce originating from the nerves of motion, 

 modified by the organization of the part or organ. 



CCXXXVIII. Every organ of the system has 

 its proper stimulus : the eye has light, the heart 

 blood, the stomach has food and its peculiar 

 secretion, and the whole of the abdominal vis- 

 cera their various agents ; but the susceptibility 

 of an organ to its stimulus will be proportionate 

 to the fasciculi derived from the nerves of sensa- 

 tion, and the energy with which it acts will be 

 according toth e number or size of fasciculi be- 

 longing to the nerves of motion, and the adapta- 

 tion of the part to promote the intended effect. 

 If we examine the structure of the iris, we shall 

 observe its radiated and circular fibres, which are, 

 by the best authorities, considered muscular ; if 

 then light be transmitted to the retina, the iris 

 contracts in virtue of its sensibility to impres- 

 sions, and the power of motion communicated 

 to its radiated and circular fibres by its nerves 

 of motion. If we examine the disposition of 

 the muscular fibres of the sphincter ani, we 

 observe that these are calculated to produce 

 the necessary effect ; or if we look to the 

 stomach and intestines, we have circular fibres 



