THE PROPERTIES OF I \<H PART OP 'rill REFLEX LRC B01 



is composed of a visoous fluid full <»r extremely minute granules, each of 

 which apparently consists of a colloidal solution surrounded by a lipoid 

 envelope (Pig. 210). When the temperature is raised, the granules dis- 

 appear, and when th lis are deprived of oxygen, the cytoplasm and 



nucleus become swollen. A similar swelling of the cell and nucleus super- 

 venes upon snt imi of the axon; and in stained specimens the Nissl 

 granules disappear and the protoplasm stains diffusely chromatolys 



In embryonic life the proc< of the nerv 'lis appear to be capa- 

 ble of undergoing a certain amount of ameboid movement, and fibers 

 grow out from them, indicating, therefore, that in the development 

 of the nervous system the nerve cells appear first, and the nerves sub- 

 sequently grow oul from them to their proper destination. Prolifera- 

 tion of isolated tissue cells m vitro lias been observed for many other 



ring nerve cells (from the <!• ■ i -:il rool ganglia "t .-, dog three icamined 



by tlir ultramicroscope. There arc no Kit - it new ' i" 



protoplasm. (From Marinesco.) 



i issues, such as cardiac muscle, renal epithelium and connective tis- 

 sue. Its occurrence indicates that the therapeutic principle that the 

 aim of treatment should be to give the diseased organ a rest so that by 

 cell regeneration i1 may r ver its lost function, is one which may ap- 

 ply tn the nerve tissues of young animals. Whether adult n< ells 

 may regenerate is as \«t no1 certain. 



This growing out of nerve fibers from their cells is t ; ential na- 



ture ut' the development of the nervous system in the developing animal. 

 At birth, unlike the cells of other tissues, those of the central nen 



system are already provided. No new ones arc added during postnfl 



life. The axons gradually develop from this inherited stock nt* n< 

 rolls, and by connecting with other neurons about the 



integration which is the important characteristic of the adult i 



