948 



were situated on tlie left and at the lop beneath the lines were 

 counted. 



A number of spiruil ganglia and pieces of the spinal cord (fixed 

 both in Flkmming and Zenkkr liquid and B. impregnated) were 

 arranged in unbroken series for investigation of the figures of cell 

 divisions (sections from 3 — 5 (i in thickness). Some spinal ganglia 

 with dorsal and ventral i-ools and a small piece of the spinal cord 

 (all B. impregnated) from animals of various ages were arranged in 

 unbroken series (longitudinal sections of the roots from 5 — 10 n in 

 thickness) for investigation as to the occurrence of 7- and J'^divisions 

 and figures of growth of the nerve fibres. 



The post-emhryonal increase in the numhev of the nerve fihres in 

 the dorsal and ventral roots of the spinal nerves. 



With regard to the general growth of whole animals from birth 

 to maturity (or at least during the period of active growth) woiks 

 have been published on (jallu<! doniesticus (Minot ^), 1908) Mns nor- 

 loegicns (dhinus (Donaldson')), Lepus cunicahis (Minot '), 1908), 

 Cavia cobaya (Minot'), 1891). Canis faniiliaris (Aron, 1911')), 

 Homo caucas (Robkkts, 1878') and othei's) and Homo nwngol. 

 (MiSHiNA, 1904 ') ), etc. All those who have studied growth have 

 also acknowledged and laid stress on the need for an analysis 

 of the total giowth into its components — the organs and their 

 elements the cells. Numerous investigations of the post-embryonal 

 development of the oi-gans and even of the cells have already 

 been published by Donaldson, Hatai, Naoki, and others. On the 

 other hand, as far as I could find from the literature, no in- 

 vestigation of a post-embryonal growth of the number of axons in 

 the nervous system seems so far to have been published. It is 

 certainly true that there are numerous investigations on the number 

 of nerve fibres in the dorsal and vential roots of the spinal nerves 

 and in a nnmi)er of cranial nerves both in full-grown animals and 

 in animals of different ages (especially M. nonoegicus albinus), by 

 Dunn, Hardksty, Hatai and others, and in Homo by Stilling, 

 Ingbert and others, but they have all been carried out with the 

 help of staining methods for medullary sheaths and so cannot afford 



') Quoted from Donaldson, H. H. An anatomical analysis of growth. Trans, 

 of the 5lli. International Congress of Hygiene Demography held at Washington 

 D. G. Sept. 23—28. 1912. 



') Donaldson, H. H., Watson J. B. and Dunn, E. H. 1906. A comparison of 

 the wliite rat with man in respect to the growth of the entire body. Boas 

 Memorial Volume, New York. 



