292 Kajiura 



reaction. Dr Donath had sent to Dr Rosenheim seven samples of 

 cerebro-spinal fluid from cases of genuine epilepvsy, and the latter kindly 

 placed them in my hands for the purpose of this research. I have to 

 thank Dr Rosenheim for his care in supervising my work. I am also 

 deeply indebted to Dr F. E. Batten, Dr A. Connel, and Dr J. Bernstein 

 for a number of other specimens which have enabled me to extend the 

 series of observations. In all cases th-e fluid was removed by lumbar 

 puncture during life. 



In order to make myself acquainted with the method, and at the same 

 time to test its reliability and sensitiveness, I carried out a series of tests 

 by adding pure choline to an artificial cerebro-spinal fluid. The latter was 

 prepared by mixing egg-albumin and dextrose in the necessary proportions 

 ^dth a solution of potassium and sodium chloride of a strength correspond- 

 ing to that found in cerebro-spinal fluid. The choline hydrochloride 

 employed was prepared from lecithin ai>d purified by repeated crystalli^- 

 tion of its mercury double salt.^ Using Rosenheim's simplified iodine 

 test,^ I have' been able to detect choline easily and with certainty when it 

 was mixed with the artificial cerebro-spinal fluid in the proportions 1 : 1500, 

 1 : 5500, and 1 : 10,500. In the last two instances, only 15 c.c. of the mixture 

 were used. Dilutions greater than 1 : 10,500 I should regard as of no 

 practical importance; but Rosenheim obtained positive results when the 

 proportion was 1 : 20,000. 



In the examination of the material sent by Dr Donath, my general, 

 plan of testing for choline was (1) to try the periodide test with the purified 

 alcoholic extract; (2) to employ Donath s micro-polariscopic method, 

 all his directions being carefully observed; and (3) to use Rosenheim's 

 original periodide test as applied to the platinum salt. 



The results are given in Table I.^ p. 293. 



In all cases Donath's test gave a positive result; a few doubly re- 

 fracting crystals could always be distinguished under the crossed nicols of 

 the polarising microscope (see fig. 2). The yield of the platinirm pre- 

 cipitate was in all cases extremely small, amourfbing usually to not more 

 than a slight haze ; so that it was necessary to wait many hours for it to 

 settle before collecting it on a filter. In no instance could the periodide 

 reaction be obtained either with the alcoholic extract direct, or from the 

 platinum precipitate. 



1 In his first communication on the periodide reaction, Rosenheim applied the iodine 

 solution to the crystals of choline platino-chloride, and found that they dissolved and were 

 replaced by crystals of choline periodide. Dr Rosenheim informs me that the mercury 

 salt may be used instead of the platinum salt for this purpose. I have further examined 

 the lead, zinc, and cadmiiun salts in the same way, and found that they all show the reaction. 

 The cadmium salt, owing to its insolubility in alcohol, seems to be the most suitable to 

 replace the platinum salt, if that should be necessary (see also F. W. Schmidt, Zeits. f. 

 physiol. Chem., liii., p. 428, 1907). Still, as Rosenheim pointed out in his second paper, it 

 is not really necessary to prepare a metallic salt first, for the iodine reaction can be obtained 

 straight from the alcoholic extract of any fluid which contains choline. 



2 Joum. of Physiol., xxxv., p. 465, 1907. 



