In 1901 Wildiers 1 made the statement that yeast will not grow in a nutrient solution containing ammonium salts as the sole source of nitrogen if the amount of the inoculating material is small. If the amount of the latter is large, fermentation soon follows, presumably because an essential nutrient material is introduced through the death and autolysis of some of the cells. To this hypothetical nutrient Wildier gave the name "bios." As the knowledge of vitamins developed, a general resemblance between the behavior of " bios " and vitamin B became apparent, so much so that the Belgian chemists who are studying " bios " have adopted many of the methods devised for the study of vitamin B2 while, on the other hand, several American workers have endeavored to use the growth of the yeast plant in a suitable medium as a quantitative test for the presence of vitamin B. The methods employed and the quantitative results obtained are discussed elsewhere. (See Ch. II).

Leaving aside the question of the identity of "bios " with any of the known vitamins, a brief summary of the work done on the effect of vitamins, or unidentified vitamin-like factors, on yeasts, moulds, and bacteria follows.

1 Wildiers, La Cellule, 18, 313, 1901. See also Liebig, Ann. Ghem. 163, 1, 137,1870; Pasteur, Ann. Ghem. phys. 05, 146, 1872; Mayer, Ann. Fhyaik. 149, Ser. 1, 293, 1871; Nigeli, Ghem. Zentr. za, 46, 188; Amend, La Cell, az, 829, 1904; Devloo, lb. 23 361, 1906; Henry, Ann. brass, et dirt. 1902, 129; Woch. brau. 19, 326, 1902.

2 Ide observes that a distinction should be made between two kinds of proliferation of yeast, one very alow without "bios" and one fast with "bios." To achieve rapid growth in which proliferation is increased 30 times a special "bioaine," specific in its influence on the growth of yeast, is asserted by Ide to be necessary for he considers that none of the known organio substances described up to the present time has any comparable influence on yeast. For rapid growth, the yeast needs a large portion of its nitrogenous food in the form of biosine. As yet, no difference has been observed in the chemical properties of the water-soluble B of Myers and Voegtlin and biosine. But it cannot be stated yet with certainty that water-soluble B vitamin and " bios" are the same substance.

Bachmann, 3Williams,4 Swoboda,5 Eddy and Stevenson6 and Funk and Dubin7 have all believed that the vitamin requirement of yeast is so definite that it may be made the basis of a quantitative test for the presence of vitamin B, although the last-named authors have now come to the conclusion that the vitamin in question is not B but a new vitamin which they call D,8 and Bachmann pointed out that anaerobic yeast could apparently develop successfully in a vitamin-free medium.

Emmett and Stockholm,9 Whipple10 and Eddy, Heft, Stevenson, and Johnson 11 agreed that vitamin preparations have a highly stimulating effect on the growth of yeast,12 but doubted the applicability of the method for quantitative determinations, while Souza and Mc-Collum,13MacDonald and McCollum,14 Fulmer, Nelson and Sherwood15 deny that a supply of vitamins is essential for the growth of the yeast plant. As in so many other branches of vitamin research the results obtained in different laboratories seem directly contradictory, but it is probable that with further knowledge a compromise is already suggested by the work of Funk and Dubin referred to above, in which they believe they have secured conclusive evidence that the growth stimulant required by yeast is not B bub another vitamin with many properties similar to those of B, but quite distinct from it in others. (See p. 150 and ff).

That water soluble B is not an essential constituent of the medium for the growth of yeast but yeast is capable of synthesizing that vitamin is indicated by the observations of Nelson, Fulmer and Cessna.16 For growing the yeast a medium was used of the following compositions:

3 Bachmann, J. Biol. Ohem. 39, 235, 1010.

4 Williams, lb. 38, 465, 1010; 42, 250, 1020; 46, 113, 1021. 5 Swoboda, lb. 44, 531, 1020.

6 Eddy and Stevenson, Proc. Soc. Exp. Biol. Med. 17, 52, 1010. 7 Funk and Dubin, J. Biol. Chem. 44, 487, 1920; 48, 437, 1021.

8 See also Emmett and Stockholm, J. Biol. Chem. 43, 287, 1020.

9 Loc. cit.

10 Whipple, J. Biol. Chem. 44, 175, 1020.

11 Eddy, Heft, Stevenson and Johnson, lb. 47, 240, 1021.

12 See also Euler and Petteruon, Z. physiol. Chem. 114, 4, 1021.

13 Souza and McCollum, J. Biol. Chem. 44, 113, 1020.

14 MacDonald and McCollum, lb. 45, 307, 1020-21; 46, 525, 1021.

15 Fulmer, Nelson and Sherwood, J. Am. Chem. Soc. 43, 186, 101, 1021.

16 J. Biol. Chem. 46, 77, 1021.

Potassium Phosphate ........ 0.1 g.

Calcium Carbonate.......... 0.04 g.

Calcium Chloride ........... 0.1 g.

Ammonium Chloride......... 0.188 g.

Sucrose .................... 10. g.

Distilled water .............. 100 c.c.

The yeast was plated from a Fleischmann yeast cake. The yeast was grown continuously in the above medium for a year. It was grown in 50 cc. portions of the medium, 1 cc. of the culture being transferred every other day to 50 cc. of fresh medium thus enormously diluting the original constituents of the medium or of the yeast. It can be concluded that after such a procedure any B present in the yeast must have been synthesised by the organism. Sufficient yeast was grown for feeding experiments on rats which made rapid gains when 2 per cent of the yeast grown on the synthetic medium was added to a ration free from B and on which the rats had begun to decline rapidly.17

Vitamins according to Lumiere 18 are not necessary to the development of plants, which reach full growth in media of known chemical composition. Extracts from substances rich in vitamins as dried raisins, aided deyelopment in media which were low in nutritive value, but their place could be taken perfectly by appropriate addition of mineral salts. Penicillium glaucum, Aspergillus niger, and Rhizopus nigricans and Amanita muscaria were used in these observations.