286 ABRAM T. KERR 



by underlining, erasing, or inserting the names n the proper 

 place. They were in many cases accompanied by free hand 

 sketches of the arrangement of the nerves and only those records 

 that were accompanied by satisfactory diagrams have been used 

 in this paper. Beginning in 1899, the records were made on the 

 Bardeen Outline Record Charts (Bardeen '00) as prepared under 

 Dr. Bardeen's direction by the writer for the upper extremity. 

 At first the outline record charts were used at Cornell but later 

 the students made natural size drawings. 



Between four and five hundred records were preserved. From 

 these I have selected only those diagrams about the accuracy and 

 scientific value of which I could feel no doubt. These number 

 175. Records have been rejected for various reasons. In some 

 cases, the condition of the dissecting material made it impossible 

 to obtain satisfactory dissections. Lack of manual dexterity 

 or careless dissection made the work of some students of no 

 value. In other cases, the inability of the student to draw 

 accurate or clear diagrams made their records worthless. A 

 considerable number of records which were otherwise accurate 

 were excluded because they did not record the relation of the 

 fourth cervical nerve to the plexus. 



It not infrequently happened that the record of the plexus as 

 a whole was satisfactory but the record of one or more of the 

 branches had to be discarded, either because the branch was 

 broken or because, at the time the record was verified, its dis- 

 tribution had not been sufficiently worked out. The record of 

 such a plexus has often been included in this series but has not 

 been used for the study of the doubtful branch or branches. For 

 this reason the number of the records of different branches 

 varies considerably. 



Although age would seem to have very little influence upon 

 the course and distribution of the nerves, nevertheless the ages 

 of the cadavers were considered. They were obtained in most 

 cases from the records. In the' remainder, they were estimated 

 as accurately as possible. They ranged from infancy to senility. 



The color of the subjects used was determined in most cases 

 from the records. Without the records it was often difficult to 



