CULTURE MEDIA ii 



the fungus could synthesize protoplasm or derive energy. Steinberg's 

 synthetic medium was adequate but not optimum for most rapid growth 

 and sporulation. We may suppose that the yeast extract and peptone 

 contained compounds the synthesis of which constituted a limiting effect 

 upon the rate of growth and sporulation. 



Synthetic media may be simple or complex but must contain the essen- 

 tial elements in utilizable form. Brefeld (1881) gave the following direc- 

 tions for preparing a synthetic medium: Add cigar ashes dissolved in 

 nitric or citric acid to a solution containing a soluble carbohydrate, such 

 as glucose, and an ammonium salt. The amount of ashes was not speci- 

 fied. The first vsynthetic medium was devised by Raulin (1869). 



Table 1. Composition of the First Synthetic Medium for CuLTrvATiNG Fungi 



(Raulin, Ann. sci. nat., Ser. V, 11, 1869.) 



Ammonium nitrate 4.0 g. 



Ammonium phosphate 0.6 g 



Magnesium carbonate 0.4 g 



Potassium carbonate 0.6 g 



Ammonium sulfate . 25 g 



Zinc sulfate . 07 g, 



Iron sulfate . 07 g 



Potassium silicate . 07 g, 



Sucrose 70 g, 



Tartaric acid 4 g 



Water 1,500 ml. 



However, not enough information is given in Table 1 for the duplication 

 of this medium. Which ammonium phosphate, (NH4)H2P04 or (NH4)2- 

 HPO4, was used by Raulin in the original work? Which zinc sulfate, 

 ZnS04-7H20 or ZnS04-H20, was used? Was the iron sulfate FeS04, 

 FeS04-7H20, or re2(S04) 3? Did he use D-tartaric, L-tartaric, DL-tartaric, 

 or weso-tartaric acid? These questions are asked for the purpose of 

 emphasizing the need for exactness in reporting the composition of media 

 used in experimental work. These uncertainties creep into the literature 

 through ignorance or carelessness, or both. Nor are these ambiguities to 

 be found only in the older literature, for they are present in papers pub- 

 lished only yesterday. Either the specific name or the formula, or both, 

 should be stated. If it is stated that dipotassium phosphate, K2HPO4, 

 was used, the reader is certain of the identity of the compound. Potas- 

 sium phosphate may designate at least five distinct chemical compounds. 



NATURAL VERSUS SYNTHETIC MEDIA 



In addition to the fact already noted that the composition of natural 

 media is unknown, natural and synthetic media differ in two further 

 respects. Natural media are more complex; i.e., they contain more 



