276 PHYSIOLOGICAL CHEMISTRY. 



extracting a brain-mass which had been previously boiled with 

 baryta- water, with boiling alcohol. Following a method essentially 

 the same, but differing somewhat, GEOGHEGAN prepared from the 

 brain a cerebrin with the same properties as MULLER'S, but con- 

 taining less nitrogen. According to GAMGEE, this cerebrin of 

 GEOGHEGAN is a mixture of the cerebrin produced by the decom- 

 position of the protagon and a substance called by GAMGEE " psendo- 

 cerebrin." Furthermore, THUDICHUM has collected together under 

 the name "cerebrine" several nitrogenized bodies free from 

 phosphorus, such as MULLER'S cerebrin and the newer bodies 

 phrenosine and kerasene. Lastly, PAKCUS has endeavored to prove 

 that the cerebrin described by both MULLEE and GEOGHEGAN" is a 

 mixture of three bodies, "cerebrin," " homocerebrin," and " en- 

 cephalin." 



From the above statements it is seen that the composition of the cerebrins 

 is still unsettled, so that we cannot admit the numerical results of any inves- 

 tigator as authoritative, nor can we even take an average as correct, and we 

 therefore give below a summary of the results thus far obtained : 



C H N 



Mailer's cerebrin 68.45 11.20 4.50 per cent 



Geoghegan's cerebrin 68.74 10.91 1.44 



Parcus's cerebrin 69.08 11.47 2.13 



Parcus's homocerebrin 70.06 11.60 2.23 



Parcus's encephalin 68.40 11.60 3.09 



Gamgee's pseudocerebrin 68.89 11.87 1.83 



Thudichum's kerasene 68.90 11.36 1.74 



As GEOGHEGAN'S cerebrin has the lowest amount of nitrogen, and as the 

 analyses of this investigator agree well with each other, it is difficult to under- 

 stand how this cerebrin can be, as PARCUS' claims, a mixture of bodies 

 richer in nitrogen which were prepared by this last-named investigator. On 

 the other hand, PAKCUS has found a constant composition for the cerebrin 

 irrespective whether it was recrystallized two, five, or eight times, and it i& 

 therefore quite as unjustifiable to question his results. Future researches are 

 required to elucidate this question. GAMGEE'S pseudocerebriu and THUDI- 

 CHUM'S kerasene have, with the exception of the amount of hydrogen, so sim- 

 ilar a composition that they may be considered as identical. 



The products of decomposition of the cerebrins possess a certain interest. 

 By the action of concentrated sulphuric acid GEOGHEGAN obtained a lasvo- 

 gyrate, reducible substance, which is not sugar but an acid. As chief product 

 a substance is obtained which he called "cetylid," C^H^O 5 , and which on 

 fusing with caustic potash yields marsh-gas, hydrogen, and palmitic acid. 

 According to him, this cetylid is probably a derivative of cetyl-alcohol. 



Of special interest is the proof, as first shown by THUDICHUM 

 and lately substantiated by THIERFELDER, that on heating the so- 

 called cerebrin with dilute sulphuric acid a glucose is split off. 



