io6 Journal of Comparative Neurology. 



cases were always referred to the microscope which often showed 

 them to be one fiber collapsed in such a way as to give its sec- 

 tion this form. 



In using the counter, the eye of the observer naturally 

 follows the point of the needle. Since a puncture is made in 

 the center of each fiber at the time it is counted, this puncture 

 is readily seen and protects the fiber from being counted a sec- 

 ond time. 



After a photograph had been counted in this way, each 

 field was examined a second time. This time the microscope 

 was used even more frequently than the first and especial search 

 was made for small fibers which might have been overlooked. 

 This search seldom added more than 2 % to the first count. 

 Finally each field of the photograph was examined with a hand 

 lens, search being made for unpunched large fibers. The hand 

 lens was an advantage both in reducing the field of view and in 

 so magnifying the fibers that one with an unpunctured center 

 could be quickly discerned. Strange to say, if any of the larger 

 fibers had been omitted in the previous counts, they were usu- 

 ally found to be the very large ones. 



When a count had been completed the number of fibers 

 found in the photograph was written below the label which had 

 been printed on it and the photograph was filed. In order to 

 more thoroughly guard against any personal equation, no two 

 sections from consecutive levels were counted in succession. 

 Sometimes the counting of two nerves was carried on simulta- 

 neously and thus in the large number of sections involved, the 

 number of fibers contained in a section from a given level had 

 passed out of mind before determining the number contained 

 at an adjacent level. 



In order to test the accuracy of the enumeration, in quite 

 a number of cases a second photograph was counted. In almost 

 every case the second number obtained was identical with that 

 of the first count. If there did result a difference in the two 

 counts it seldom amounted to i 'fo and the fibers causing the 

 difference were always found. 



