406 SPECIAL HISTOLOGY. 



found in small quantity in the grey substance, constitutes in 

 every case the opaque granules in the cells, and appears to 

 exist in other conditions also, in their contents. When isolated 

 nerve-cells are compressed, they become much flattened, re- 

 suming their pristine form when the pressure is removed. 

 Their processes also are very elastic, and like the axis-fibres 

 may be considerably extended, and afterwards again retract 

 themselves. 



As our knowledge of the chemical composition of the grey 

 and white substance still leaves much to be desired, I content 

 myself with the following statements. Lassaigne, in the brain 

 of a lunatic, found — 



According to Fremy (Comptes rendus, torn, ix, p. 703, 

 r Ann. d. Chem. und Pharm. 1841,' vol. xl, p. 69), the brain 

 (both substances together) contains — 



Water 80 



Albumen ........ 7 



Fatty matter 5 



Osmazome and salts ...... 8 



100 



Which almost exactly agrees with Yauquelin's analysis, who 

 moreover estimates the osmazome at L12, and the salts at 

 6*65; whilst it differs from that of Denis, who found much 

 more fatty matter (12*40 in man 20 years old, 133 in one 

 aged 78), and less water (78 and 76g). 



CENTKAL NERVOUS STSTE3I. 



§ H2. 



Spinal Cord. — The nervous elements are so disposed in the 

 spinal cord, that its external, white substance is constituted 

 almost exclusively of nerve-fibres, whilst the grey nuclear por- 



