MINUTE STRUCTURE OF THE BACTERIAL CELL 6 1 



cannot be satisfactorily applied to them. It is well known 

 that the chemical constitution of the bacterial cell varies 

 greatly in different species, and in the same species when the 

 bacteria are grown on different varieties of culture media, 

 and on the same media. The chemical constitution also 

 varies with the age of the bacteria. The following from Wells, 

 " Chemical Pathology," quoting Cramer, gives a very good 

 statement of their composition. Cholera vibrios grown on bouil- 

 lon on analysis showed 65.25 per cent proteid and 25.87 per 

 cent ash. When grown on media free from protein (Uschinsky's 

 medium) they showed 35.75 per cent protein and 13.7 per cent 

 ash. In the same medium 65.63 per cent and 34.37 per cent 

 protein were noted in two strains of cholera vibrios. It can- 

 not be said that any one species of bacteria has a definite 

 chemical structure. However, there are some chemical sub- 

 stances which are found in the same species of bacteria con- 

 tinuously, as, for example, the fats in acid-fast bacteria. The 

 variation in structure is more quantitative than qualitative. 



The older analyses, of which there are many, are on the 

 whole incorrect in the light of modern methods of research. 

 The majority of bacteria contain liquids, proteins, water, and 

 salts, such as those of sodium, potassium, magnesium, and phos- 

 phorus. Phosphorus in all probability occurs in the largest 

 amounts. According to a recent investigation of Iwanoff the 

 principal constituent of the bacterial cell is a genuine nucleo- 

 protein containing traces of iron and sulphur. Another 

 writer, Nishimura, has reported the finding of certain purin 



