242 Latham : Assimilation of Sterigmatocvstis 



grown on a decoction of beet sugar, sugar, and some nitrogen 

 source ; while the gain for Mucor was 2.0699 mg. Ternetz in 

 work with the '^ Oxycoccits-YAz'' found a gain of 3.2994 mg. of 

 nitrogen. These are the more recent researches on the subject. 

 In 1893, Berthelot wrote that in working with Aspergillus he had 



r 



determined a gain of 26 per cent, in a certain culture, the crop 

 giving an absolute gain of 7 mg. The figures we have been able 

 to obtain have showm as high as 205 mg. in one instance, the 

 lowest amount being 1.6 mg., but the total average is 72.2 mg. for 

 five control cultures and 48,3 mg. for cultures at the optimal 

 stimulation. These numbers in nitrogen analysis are not open to 

 the objection made by the critics cited above, and by others. 

 They are indeed rather large for nitrogen determinations. 0( 

 course they include all the nitrogen in the culture, both that ex- 

 creted into the nutrient solution, and that entering into the make- 

 up of the vegetative body as well as the original supply. The 

 largest amount gained in solution was 193.6 mg. over and above 

 the 1 17.7 mg, supplied. 



Proofs of accuracy in the operations may be adduced from the 

 facts that examinations of different specimens of a felt made at 

 times at some interval from one another gave results which varied 

 by only a small fraction of a milligram ; and examinations of the 

 reagents at different times were fortunate in the same respect. 

 Again, the different results constantly obtained with normal and 

 stimulated crops, all at the same time consistent within them- 

 selves, would seem to give further indication of some success in 

 manipulation. So that on the whole, it is hoped that this work 

 will be considered as having measurably confirmed the results of 

 the earher workers with normal cultures ; and also as having 

 brought forward some data of value, namely, that while stimulated 

 crops behave more economically with regard to their carbohy- 

 drate consumption, and while the amount of nitrogen entering 

 into the composition of the fungal felt is relatively the same as for 

 a normal growth, yet with regard to their nitrogen relation these 

 stimulated cultures are less thrifty than normal ones, which, unless 

 the nitrogen supplied them be in too great quantity, are able to 

 use gaseous nitrogen and to bring it into chemical combination 

 even in excess of actual need. 



