Editorial. 465 



these were taken as the units — not the neurone, not the segment 

 or neuromere or any artificially bounded region, but the aggregate 

 of nervous centers and tracts which act together for the perform- 

 ance of some definite function. The result was the most acces- 

 sible compend of data and literary references regarding the struc- 

 ture of the human brain which has ever been published. 



But some years before the appearance of Dr. Barker's book a 

 movement was inaugurated in the field of comparative neurology 

 which was designed to define these functional units much more 

 accurately and by comparative studies to outline their phylogeny. 

 This movement began naturally and properly with the analysis of 

 the peripheral nerves and their primary centers, and hence was 

 termed the doctrine of nerve components. The simplicity of 

 organization thus revealed in the peripheral nervous system gave the 

 key to a similar functional analysis of the central nervous system 

 with still more gratifying results. 



In brief, the functional analysis of the nervous system, in the 

 form in which it has grown up within the past decade, has furnished 

 us with the unifying principle necessary to organize comparative 

 neurology into a truly scientific discipline and at the same time 

 make it really effective as the hand-maid of human neurology. 



This movement was born in America and has been largely cul- 

 tivated here. It is still too young to permit a final adjudication 

 of its merits; but that was a significant remark made by a careful 

 and patient observer, Dr. Kappers, in our issue for last January. 

 He admits that he began his studies on the brains of fishes pre- 

 judiced against the ideas of what he terms the "American school;" 

 but when his research was completed he states that he found no 

 facts inconsistent with these views and he is in fact cordially appre- 

 ciative of this work. 



In view of the importance of the role played by American stu- 

 dents in the elaboration of the newer phases of this functional 

 analysis, it is fitting that the first comprehensive text-book of com- 

 parative neurology written from this point of view should appear 

 in this, country. In Professor Johnston's "Nervous System of 

 Vertebrates," a more extended notice of which appears in our re- 

 view columns, we have the most consistent and satisfactory appli- 

 cation of the genetic method in comparative neurology which has 

 yet been made. Each functional system is first taken separately 

 and given a searching analysis in representative types and then 



