[Vol. 10 



348 



ANNAL8 OF THE MISSOURI BOTANICAL GARDEN 



and Sphaeropsis the precipitate was largely Mgi(P04)i4H»0, as 

 the NHi content of these cultures does not reach an appreciable 

 quantity until late in the incubation, when most of the Mg and 

 P0 4 ions have been precipitated. The appearance of the charac- 

 teristic crystals of the salts maybe considered as a rough indication 

 of the beginning of an alkaline reaction which, for the most part, 

 results from predominance of autolytic processes. The reduction 

 in active acidity necessary to their formation was determined 

 experimentally by adding NH«OH or KOH to the media; the 



rs 

 p — • 



HH, NQ,- 

 KNOj ■ ■ ■ 



• ... . 



■•«.* . 



* ■» '<..„- 



£ J ■* J 6 4 S Q it it 



18 



PAYS 



Fig. 8. Dry weights of fungous mats. Diplodia tuitalensis 



crystals were centrifuged out and identified by microscopic 

 comparison with known salts and by analyzing quantitatively 

 for N content and qualitatively for the ions present. Crystals 

 appeared at P H 6.1 in the presence of NH,; that is, when NH«OH 

 was added to the media, or KOH to media 3 and 4 which con- 

 tained NH« salts, these were identified as MgNH 4 P0 4 .6HiO. 

 When KOH was added to media 1, 2, and 5, crystals were not 

 formed until the exponent P H 7.1-7.2 was reached; these were 

 Mg.CPOO.^H.O. 



The causes of the slight fall in the Ph curve of the "peptone 

 minus" cultures of Aspergillus niger during the first 3 days of 

 incubation is problematic. Possibly during rapid formation of 

 protoplasm of the young mycelial threads the NH t group of the 



