512 M. J. GREENMAN 



distribution of the fibers in the nerve near the lesion and also 

 show that the increase in number begins high up in the course 

 of the proximal portion of the nerve. The fate of these excess 

 fibers has not yet been determined. 



The most important outcome of this investigation is the evi- 

 dence it furnishes of an alteration in the number and size of 

 the fibers in the control nerve and in the proximal end of the 

 operated as well as the accompanying changes in the diameter 

 of the fibers and the area relation of the axis-sheath. 



These alterations, as they stand, apply to symmetrical periph- 

 eral nerves, but it seems possible that they are more widely 

 distributed. The sensitiveness of the area relation of the axis- 

 sheath to disturbance of the normal conditions in the animal 

 points to a high degree of nutritive response in the medullated 

 fiber. ^ 



LITERATURE CITED 



Boll, Feanz 1876 Studi sulle immagini microscopiche della fibra nervosa 

 midollare. Nota del Prof. Franz Boll presentata dal Socio Tommasi- 

 Crudeli nella seduta del 4 giugno. 



BouGHTON, Thomas H. 1906 The increase in the number and size of the medul- 

 lated fibers in the oculomotor nerve of the white rat and of the cat 

 at different ages. Jour. Comp. Neur., vol. 16, no. 2. 



Cajal, S. Ram6n 1913 Estudios sobre la degeneracion y regeneracion del sis- 

 tema nervioso. Imprenta de Hijos de Nicolas Moya. Madrid. 



Donaldson, H. H. 1903 On a law determining the number of medullated nerve 

 fibers innervating the thigh, shank and foot of the frog, Rana vires- 

 cens. Jour. Comp. Neur., vol. 13, no. 3. 



Donaldson, H. H., and Hoke, G. W. 1905 On the areas of the axis cylinder 

 and medullary sheath as seen in cross sections of the spinal nerves of 

 vertebrates. Jour. Comp. Neur., vol. 15, no. 1. 



Dunn, Elizabeth Hopkins 1900 The number and size of the nerve fibers in- 

 nervating the skin and muscles of the thigh in the frog (Rana virescens 

 brachycephala, Cope). Jour. Comp. Neur., vol. 10, no. 2. 

 1902 On the number and on the relation between diameter and distri- 

 bution of the nerve fibers innervating the leg of the frog (Rana virescens 

 brachycephala. Cope). Jour. Comp. Neur., vol. 12, no. 4. 

 1909 A statistical study of the medullated nerve fibers innervating 

 the legs of the leopard frog (Rana pipiens) after unilateral section of 

 the ventral roots. Jour. Comp. Neur., vol. 19, no. 6. 

 1912 The influence of age, sex, weight and relationship upon the 

 number of medullated nerve fibers and on the size 6f the largest fibers 

 in the ventral root of the second cervical nerve of the albino rat. Jour. 

 Comp. Neur., vol. 22, no. 2. 



