MUSCULAR SYSTEM 



As might be expected, we find, in the 200 to 250 muscles 

 which form the active motor apparatus of the human body, 

 variations far greater and more numerous than any already 

 described in the different parts of the skeleton. 



It may confidently be asserted that hardly a single human 

 subject has been examined which has not shown some variation 

 or other in the muscular system ; and in a great number of 

 bodies new muscles are discovered which have not before been 

 observed, and of which no mention can be found in text-books. 



Considering this " embarras de richesse," we may be excused 

 for entering in the following pages somewhat into detail ; it is, in 

 fact, absolutely necessary to do so in order to get a general idea 

 of the immense mass of material available. Of the extent of this 

 variation an approximate idea may be obtained from the fact 

 that my French colleague Testut, in his work of 900 pages on 

 the muscular anomalies in Man, has by no means exhausted the 

 subject. 



Examples will be considered in the following order : 



(1) Retrogressive or vestigial muscles. 



(2) Muscles which, appearing only occasionally, are considered 



to be atavistic. 



(3) Progressive muscles. 



This order cannot be rigidly adhered to, inasmuch as both 

 progressive and retrogressive development have been observed to 

 take place, side by side, in one and the same muscular region. 

 It is further to be noted that those muscles which are actually 

 progressive as far as the genus Homo is concerned, are not recog- 

 nisable as such in mere individuals ; their anomalous conditions 

 can only be considered as individual variations until traced 

 through successive generations, i.e. until it is proved that they 

 are inherited. 



An accurate knowledge of Comparative Anatomy and Ontogeny 



