ON SO-CALLED " PROTAGOX " By Otto Rosenheim and ^I. Christine 

 Tebb. (From tlie Physiological Laboratory, King's College, London.) 

 (With one Plate.) 



{Received for publication 31st July 1908.) 



[n the first number of this Journal ^ Wilson and Cramer made an attempt 

 to rehabilitate " protagon " as a substance of definite chemical composition 

 and of constant physical properties. For this purpose the old assumption 

 of Liebreich, previously abandoned by Cramer, that " protagon " is decom- 

 posed by warm or boiling alcohol, is revived. The decomposition is assumed 

 to be a hydrolytic one, and explains, according to Wilson and Cramer, the 

 discrepancies in the analytical figures obtained for " protagon " by other 

 investigators. By means of a method which is essentially a modification 

 of Couerbe's (1834) original method for the preparation of what he called 

 c^r^brote^ ( = " protagon "), and by limiting the time of extraction to one 

 aiid a half minutes, they prepared a new standard " protagon " and maintain 

 that it can be recrystallised from alcohol without decomposition, the only 

 condition being to limit the action of the solvent to a short period of time. 

 As an index of the decomposition they rely upon a change in the supposed 

 physical constants. The specific rotation of " protagon " in pyridine is 

 stated by Wilson and Cramer to be [a]^-^^ -j-G'S^, whilst " decompo.sed 

 protagon" according to them shows [aj: = { + 1)m^° (1308 to 13-43). By 

 a strange oversight the sign of the rotation in the latter case is not stated. 



In the course of an investigation on the behaviour of " protagon " 

 solutions in polarised light, which has led us to the discovery of a new 

 phenomenon (Spherorotation), we have found that any " protagon " (pro- 

 vided that its constituents are present in such proportions as to make the 

 amount of phosphorus about 1 per cent.) possesses an initial dextrorotation 

 of [a]n = -f6-8° and a final Isevorotation of [a]™ = —13-3".^ This change 

 from dextrorotation to Isevorotation, the nature of which has been 



» Journ. of Exp. Physiol., vol. i., 1908, p. 97. 



2 It .soeni.s hardly necessary, in view of the results to be discussed in the present 

 paper, to enter into tlie charge of inconsistency made by Wilson and Cramer against our 

 identification of "cerebrote" and " acetone- protagon '' with "protagon." It can be easily 

 shown by the methods to be described that the.se two products represent the same hetero- 

 geneous mixtures as, and are identical with, "protagon." With regard to the different 

 solubility of "protagon" in acetone before and after extraction from brain, Wilson and 

 Cramer seem to have forgotten that exactly the .same behaviour of " protagon " towards 

 ether was de.scribed in Liebreich's original pa]>e,r. This is, indeed, now generally recognised 

 as characteristic of the behaviour of mixtures of lijwids. 



^ Journ. of Physiol., vol. xxxvii., 1908, p. 341 and p. 348. 



