Dunn, Medullated Nerve Fibers. 695 



ascertained at the time of operating and when obtained showed 

 undoubted loss of weight in the frog due to its eight months of fast. 



The control, frog I IB, was a female, length 234 mm., corrected 

 weight 61.5 grams. 



If we consider first some general statements regarding the findings 

 for frog E, Table HE introduces the counts at the levels of interest 

 in the main trunks of the nerves innervating the leg. The distri- 

 bution of nei"ve fibers to the leg in the frog is by the nervus cruralis 

 and the nervus ischiadicus. All the nerve fibers of the nervus 

 cruralis are distributed to the thigh, while the nervus ischiadicus, 

 after giving off its thigh branches, divides in the lower third of the 

 thigh into the nervus tibialis and the nervus peroneus which furnish 

 branches to the shank, then subdivide and cany nerve fibers to the 

 foot. 



Counts of both the cruralis and the ischiadicus at the entrance 

 level of the thigh, of the ischiadicus below its thigh branches, of the 

 tibialis and peroneus at the entrance to the shank, and of their sub- 

 divisions at the ankle, permit calculations as to the probable number 

 of medullated nerve fibers innervating the tissues of each segment 

 of the leg, and at these levels counts w^ere made and entered in 

 Table III. 



In addition counts were made of the medullated nerve fibers in 

 the various primary branches. Table IV contains the counts for 

 the thigh. Here further differentiation has been made between those 

 branches innervating muscles and those innervating skin. Table V 

 deals in the same way wath the branches to the shank. These three 

 tables contain in brief all the data which we possess for frog E 

 dealing with the matter of enumeration. Additional tables for frog 

 E have been introduced only for the sake of clarifying or emphasiz- 

 ing certain points. 



Three corresponding tables from the findings for frog IIB are 

 introduced for control. These tables are modified from former 

 tabulations given on pages 311-317, Dunn, 1902. They are Tables 

 VI, VII, and VIII, pp. 692, 693. 



The most obvious information gained by a glance at the three tables 

 for frog E is this, that while certain branches show almost identical 



