634 SCIENCE PROGRESS 



and whether the compound is freshly prepared or not. Thus 

 in the case of the hydroxypyridine this substance can exist in 

 two tautomeric forms having the same melting point ; one of 

 these crystallises in needles, while the other is granular. The 

 former alone is capable of exerting any curative effect, and was 

 successfully employed on fourteen birds suffering from poly- 

 neuritis, but the granular form failed to act under varying 

 conditions in the case of fifty pigeons. The needle form changes 

 into the granular form, especially in the presence of moisture. 

 On the other hand the granular form may be converted into the 

 crystalline or needle form by melting slowly, cooling, and then 

 crystallising from a mixture of benzene and light petroleum, 

 but this change cannot apparently be effected by the animal 

 organism. The instability of vitamines contained in food- 

 stuffs may be due to some tautomeric change of the above 

 nature. In a subsequent paper entitled " Isomerism in Natural 

 Antineuritic Bodies " (/. Biol. Chem. 191 6, 26, 431) the author 

 states that he has been able to isolate from autolysed yeast a 

 substance having antineuritic properties. This substance, which 

 melts at 345 ° C. if crystallised from hot water, changes its crys- 

 talline form, and thereby loses its antineuritic properties, and 

 in this condition it has been identified as adenine. When 

 adenine is fused or heated with alcohol in a sealed tube for 

 three hours at 1 8o° C. it recovers its antineuritic power. The 

 active substance is distinguished from the inactive one by 

 giving a blue colour with Folin's reagent, phosphotungstic acid, 

 and sodium carbonate, and it may be concluded that the 

 active compound is an isomeride of adenine. 



In the same connection it may be noted that Abderhalden 

 and Ewald (Zeitsch. Gesamte expt. Med. 1915, 5) have found 

 that methylglyoxaline added to the diet induces symptoms 

 similar to those of polyneuritis brought about by a diet 

 deficient in vitamines, but on the addition of vitamines fatal 

 results were rare. On the other hand, vitamines produced no 

 improvement in disorders brought about by the addition of 

 aminomethylglyoxaline to a diet. 



In the July number of Science Progress reference was made 

 in these notes to some observations by Katz on the hardening 

 of bread. The same author has now (Zeitsch. physiol. Chem. 

 191 5, 96, 314) made the rather remarkable observation that 

 breadcrumbs suspended in a closed vessel containing a small 



