RELATIONS OF SPEECH TO HUMAN PROGRESS 527 



ment of speech has marched pari passu with human progress. 

 Of the brain machinery involved in articulate speech we can 

 never know much. We have learned that there is a kind of 

 speech centre (or more probably a kind of nervous clearing 

 house in the to-and-fro traffic of reflex action) in the third 

 anterior frontal convolution at the left side of the average 

 brain. The skull interiors of primitive men and apes have been 

 diligently examined to see how they differ in this region, and 

 guesses have been based on what has been found as to whether 

 in this or that being articulate speech was possible. Personally 

 I do not think this line of investigation is likely to lead us very 

 far unless we get a much more accurate knowledge of how the 

 brain works and where are the actual centres for the bewildering 

 multitude of reflexes and other media of co-ordination which are 

 brought into play when we talk. 



Moreover, it must be remembered that speech is almost 

 purely artificial, and is an exceedingly modern invention from 

 an evolutionary point of view, and that it is working perforce 

 through certain primeval mechanical media which existed before 

 it began. 



We are on much more solid ground when we come to deal 

 with man's outward organs of speech, such as the larynx and 

 the tongue. As regards the larynx I do not think that any very 

 great changes can be pointed out in the way of structural 

 elaborations which are due to our human needs. With the lips 

 and tongue, however, it is very different, especially as regards 

 the muscular attachments of the latter. The writer, after study- 

 ing the subject for a good many years, has become firmly 

 convinced that a muscle which appears to have been almost 

 totally ignored by the anatomists, except as a mere protruderer 

 and withdrawer of the tongue, is one of the most important 

 factors in articulate speech. This is the genio-glossus, which 

 takes its origin by a little tendon from a point inside our lower 

 jawbone about half-way between the roots of the incisor teeth 

 and the point of the chin. 



This tendon almost immediately divides into a number of 

 muscular fibres or bundles, which spread out like a fan from 

 before backwards, and run up through the fleshy part of the 

 tongue, from its root to its tip, until they terminate quite near 

 the upper surface. Certain of the lower fibres go almost 

 straight back from the lower jawbone to the hyoid bone which 



