424 NEUROKERATIN. NUCLEIN. [BOOK I. 



40 C., for six hours, in a similar trypsin solution which has been rendered 

 alkaline. The residue is washed with cold, and afterwards with hot, 

 solution of sodium carbonate, and then extracted with a J p. c. solution of 

 caustic soda. The extracted matter is treated with a little acetic acid, 

 with the object of removing adhering alkali, and is then washed with 

 alcohol and ether. The residue presents the appearance of a yellowish 

 powder which amounts to from 15 to 20 p. c. of the dried residue left 

 after the brain has been fully extracted with alcohol and ether. 



Pro erties Neurokeratin resembles in its general behaviour the 



keratin of the horny tissues ; it differs from that 

 substance, however, in being less easily soluble in boiling solutions of 

 caustic potash. 



When boiled with, dilute sulphuric acid for some hours neuro- 

 keratin does not, like horn, entirely dissolve. In the solution, both 

 tyrosin and leucin are found ; the former being in larger and the latter 

 in smaller quantities than when proteids are similarly treated. 



Neurokeratin emits, when ignited, the odour of burning horn ; it 

 melts and then burns with a luminous flame. The body contains 

 nitrogen and 2'93 per cent, of sulphur, and leaves T6 per cent. 

 of ash. 



Nuclein. 



. When describing the constituents of pus, the propriety of admitting 

 the existence of a definite chemical individual termed nuclein was 

 discussed, and the conclusion arrived at, that under that term bodies 

 of the most varied composition had been classed, the common proper- 

 ties of which consisted in resisting the action of the digestive ferments 

 whilst they were soluble in weak solutions of caustic soda. By 

 following processes essentially similar to those by which the alleged 

 nuclein has been separated from pus, v. Jaksch 1 thinks he has 

 discovered nuclein in human brain. 



His analyses do not agree with any of the analyses of nuclein obtained 

 from other sources (see p. 242). As v. Jaksch alleges that his body 

 possessed the properties of Miescher's nuclein obtained from the milt 

 of salmon, we quote the ultimate analyses of Miescher's and v. Jaksch's 

 substances. 



ANALYSES OF NUCLEIN, 



From spermatozoa of salmon. From human brain. 



Miescher. v. Jaksch. 



(1) (2) 



C. 3611 50-6 50-5 



H. 5-15 7'4 7-8 



N. 13-09 13-21 13-15 



P. 9-59 171 208 



1 v. Jakscb, "Ueber das Yorkommen von Nuclein im Menschengeiiim." Pfliiger's 

 Arehiv, Vol. xin. p. 469. 



