388 THE NERVE-TISSUE. 



presence of smaller amounts of lecithins in the embryonic brain, 

 as 'compared with the adult brain, and notably the gray matter, is 

 now generally explained upon the assumption that the material 

 in question is in some manner intimately concerned in the growth 

 of the cellular elements proper. 



ANALYSIS OF BRAIN-TISSUE (Baumstark). 



White matter.* Gray matter.* 



Water 69.53 77.00 



Solids 30.47 23.00 



Insoluble albumins and connective-tissue . . 5.00 6.08 



Neurokeratin 1.89 1.04 



Nucleins 0.29 0.20 



Protagon 2.51 1.08 



Cholesterins, free 1.82 0.63 



Cholesterins, combined 2.69 1.75 



Mineral salts 0.52 0.56 



Other substances, soluble in ether 30.47 23.00 



ANALYSIS OF THE MINERAL SALTS (Geoghegan). 



Chlorine 0.42 1.06 



Phosphoric acid (PO 4 ) 0.85 1.39 



Carbonic acid (CO 3 ) 0.25 0.33 



Sulphuric acid (SO 4 ) 0.14 0.13 



Phosphate of iron (Fe 2 (PO 4 ) 2 ) 0.09 0.30 



Calcium 0.02 



Magnesium 0.06 0.07 



Potassium 0.58 1.52 



Sodium . . . 0.45 0.78 



Arsenic traces. 



Albumins. Of the character of the individual albumins which 

 occur in nerve-tissue very little is known. Baumstark states that 

 they are essentially the same as those of muscle-tissue, and, to judge 

 from the researches of Petrowski, it appears that one of these may 

 be identical with myosin, as it is soluble in dilute saline solution, 

 and can be precipitated by diluting with water or by salting with 

 sodium chloride. The coagulation-point of the substance has, how- 

 ever, not been determined. It is said to occur both in the gray and 

 the white matter. 



More recently Halliburton claims to have isolated two neuro- 

 globulins, both from the white and the gray matter, with a coagu- 

 lation-point of 47 and 75 C., respectively. In addition he found 

 a nucleo-albumin in the gray substance, with 0.5 per cent, of phos- 

 phorus, which coagulated between 55 and 60 C. v. Jaksch 

 further claims to have isolated a nuclein from the gray matter which 

 contains but little phosphorus, and yields hypoxanthin, xanthin, 

 phosphoric .acid, and an albuminous body on decomposition. 



The albumins, as I have indicated, are principally found in the 

 gray matter of the brain, and constitute about one-half of the 

 dried substance. In the white matter, however, they are also found, 

 though in much smaller amount, and it is thought that the cylinder 



1 The complete separation into gray and white matter is, of course, impossible. 



