BRAIN AND NERVES. 583 



The above assumption has not sufficient foundation and is less prob- 

 able, as FALK l has found cerebrosides in the medullary nerve fibres as 

 well as in nerves without medullas. These latter yielded much less 

 substance on extraction than the medullary, namely 11.51 per cent 

 extract as compared to 46.59 per cent. The extract of the first was 

 poorer in cerebrosides, but richer in cholesterin, cephalin and lecithin, 

 as shown by the following figures. 



Non-medullary fibres Medullary fibres in 



in p. m. of the total p. m. of the total 



extract extract 



Cholesterin 470 250 



Cephalin 237 124 



Cerebrosides 60 182 



Lecithins 98 29 



According to NOLL the white substance of the spinal marrow is some- 

 what richer in protagon than the brain, and in nerve degeneration the 

 quantity of protagon diminishes. The method used by him would not 

 allow of an exact determination of the disputed substance protagon. 

 MOTT and HALLIBURTON 2 have also shown that in degenerative diseases 

 of the nervous system the quantity of substances containing phosphorus 

 diminishes, and that in these cases, especially in general paralysis, choline 

 passes into the cerebrospinal fluid and the blood. In degenerated nerves, 

 the quantity of water increases and the phosphorus decreases. On 

 comparative investigations of the central nervous system of normal 

 persons and those afflicted with dementia prsecox (5 cases), KOCH 3 

 found that the variation from the normal composition was not great 

 enough nor so constant that positive conclusions could be drawn 

 therefrom. 



The quantity of neurokeratin in the nerves and the different parts 

 of the brain has been carefully determined by KUHNE and CniTTENDEN. 4 

 They found 3.16 p. m. in the plexus brachialis, 3.12 p. m. in the cortex 

 of the cerebellum, 22.434 p. m. in the white substance of the cerebrum, 

 25.72-29.02 p. m. in the white substance of the corpus callosum, and 

 3.27 p. m. in the gray substance of the cortex of the cerebrum (when 

 free as possible from white substance). The white is decidedly richer 

 in neurokeratin than the peripheral nerves or the gray substance. Accord- 

 ing to GRIFFITHS, 5 neurochitin replaces neurokeratin in insects and crus- 

 tacea, the quantity of the first being 10.6-12 p. m. 



1 Falk, Bioch. Zeitschr., 13. 



2 Noll, Zeitschr. f. physiol. Chem., 27; Mott and Halliburton, Philos. Transactions, 

 Ser. B, 191 (1899), and 194 (1901). 



3 Arch, of Neurology, 3. 



4 Zeitschr. f . Biologie, 26. 



5 Compt. rend., 115. 



