10 PHYSICAL EXPKESSION. 



A certain number of facts in physiology and 

 pathology are referred to in chaps, vi. and vii. It is 

 only by the study of such facts that the significance 

 and explanation of the modes of expression in man 

 can be elucidated, and I hope that the principles 

 defined may be applicable to the description of 

 certain pathological states, especially such as chorea 

 and epilepsy. Pathological anatomy alone does not 

 explain these ; probably they will be best described 

 in terms of movements and analyzed by these 

 signs. Direct analogy may be made between the 

 area of nerve-muscular signs in hemiplegia from a 

 destructive lesion of brain, and one-sided chorea, 

 and brain fatigue or excitement affecting the two 

 hemispheres of the brain unequally (see chap. vii.). 



The chapter (xv.) on the analysis of expression 

 gives examples of the application of these studies 

 to matters of daily life. It is in particular hoped 

 that this account will be of use to those who study 

 children, and need to read in their outward expres- 

 sion the actual state of their nerve-system. 



Artists and those who give literary descriptions 

 of the mental and emotional conditions of man 

 have taught us much, and to them the study of the 

 modes of expression is a necessity (see chap. xvii.). 

 Certain extracts have been given (see chap, xviii.) 

 from some of the older writers, which show that, 

 though modern knowledge may make it more easy 

 to speak with precision of the principles involved 

 in expression, still the matter has long been studied 

 and the thoughts here formulated have been long 

 extant. A bibliography is attached to chapter xviii. 



