336 J. HOWARD MUELLER 



It may be evaporated nearly to dryness, and after standing over 

 night on ice to allow tyrosine to separate, may be filtered, the 

 tyrosine washed out thoroughly with cold water, and the filtrate 

 and washings, which still contain the active Y, evaporated fur- 

 ther, with small additions of alcohol, to crystallization. The 

 material which separates in the first crystallization is made up 

 of microscopic round plates or spheres with no definite crystal 

 form. After one or two recrystallizations these are seen to be 

 made up of needles, and finally they crystalUze out as shining, 

 colorless, microscopic leaflets, often with obtuse angles and sev- 

 eral sided, for the most part in rosettes; but when single crystals 

 can be made out, they are hexagonal. These crystals are appar- 

 ently a new amino acid, containing sulphur, and a detailed 

 account of their composition and properties will appear shortly. 

 Unfortunately, it cannot at this time be stated definitely that 

 they constitute the Y substance. The earlier crops of indefinitely 

 crystalhne material are highly active, as are also the mother 

 liquors. A quantity of soUd weighing as Uttle as 0.00001 gram 

 has reactivated 25 cc. of a mixture of decolorized infusion and 

 glucose salt solution in the presence of an active X preparation. 

 However, on further recrystallization the activity is apparently 

 lost, but the activity of the mother liquor also slowly disappears, 

 and it is, therefore, not yet clear whether the sulphur containing 

 crystals are some tautomeric form or oxidation product of the 

 Y, or whether they are in no way related. In the meantime, a 

 study of the properties of the sulphur compound will perhaps 

 lead to methods by which it will be possible to answer this 

 question. 



DISCUSSION OF RESULTS 



Since pathogenic bacteria such as the streptococci are biologi- 

 cally adopted to growth on animal tissues, it is more than prob- 

 able that the chemical substances required by them for growth 

 are constituents of the animal body and hence probably of im- 

 portance in animal life. It is evident that studies on the cultural 

 requirements of such bacteria may, therefore, lead to results 

 equally as important to the student of animal nutrition as to 



