45 o SCIENCE PROGRESS 



by the surrounding medium resulting in the formation of a 

 compound which cannot be resolved by acids or alkalies. A 

 globulin such as is contained in horse-serum can, as a rule, be 

 converted into an antitoxin by heating with a toxin in presence 

 of sodium chloride to act as a catalyst. Thus if 3 c.c. of a toxin 

 are heated with 3 c.c. of normal serum and 0-36 gram of sodium 

 chloride for from three to thirty-six hours, the serum is converted 

 into the antitoxin provided such a substance exists, and the 

 product will be atoxic. To test this a quantity of the product 

 considerably in excess of the lethal dose is injected into the 

 aural vein of a rabbit or porpoise, and at the same time an equal 

 amount of the toxin without serum is injected into another 

 animal as a control experiment. If in the former case the 

 animal survives while the other one dies, an antitoxin has been 

 produced and immunisation of the animals may be effected, 

 but if the animal dies there is no antitoxin for that particular 

 toxin. In this way the author has been able to prove the 

 formation of antitoxins for diphtheria, tetanus, and botulismus 

 or meat poisoning, but not for the poisonous alkaloids strychnine 

 and morphine. 



The observation of Danysz that when a toxin is gradually 

 added in portions at a time to an equivalent amount of antitoxin 

 the former is not neutralised but remains poisonous, is explained 

 by assuming that the toxin is able to adsorb physically more 

 antitoxin than it can neutralise chemically. Thus for ex- 

 ample, if m molecules of toxin adsorb (n -f p) molecules of 

 antitoxin, a neutral substance T m A n + pA is formed containing 

 an excess of adsorbed antitoxin pA which however is unable to 

 neutralise any further toxin, although the latter must of neces- 

 sity be present, and the resulting system consequently remains 

 toxic. 



A good deal of confusion has existed hitherto with regard to 

 the use of the term lecithin, and it is now shown by H. Maclean 

 (Biochem. J ., 1915,9, 351) that the substance usually described 

 as " lecithin " obtained by extracting tissues with alcohol is 

 in reality a mixture of two phosphatides contaminated with a 

 complex nitrogenous impurity which it is very difficult to 

 remove, and contains substances of a purine nature ; by the 

 fractional crystallisation of the cadmium chloride compound 

 of this " lecithin " from ether it can be separated into true 

 lecithin of the formula 



