(1) The authors have studied on the application of their nitrite-medium for the classification of black aspergilli.
(2) 2-5 days' incubatioll of the agar slant culture at 30-37°C is sufficient to establish a distinction between the growth rates of the moulds.
(3) The species, which grow luxuriantly on the new medium, are Asp. aureus, Nakazawa; Asp. japonicus, Saito and Asp. batatae, Saito, while Asp. luchuensis, Inui attains a moderate growth. Asp. awamori, Nakazawa; Asp. ficuum, Hennings; Asp. fuscus; Asp. niger, Van Tiegem; Asp. niger var L; Asp. niger var S; Asp. pulverulentus, McAlpine and Asp. carbonarius, Bainier give scarcely any sign of growth within the cultural conditions given above.
(4) Black Aspergilli may be divided in two groups (or in three groups) by means of the nitrite-medium.
(5) Asp. luchuensis is distinguished from Asp. awamori by the diffenent adaptability for the new medium.

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(1) A method for the estimation of nitrite in presence of nitrates is devised.
(2) In the medium, which contains natrium nitrate as its sole nitrogen source, the nitrite is formed by Asp. Oryzae A, Takahashi.
(3) The Oxidation of the Nanitrite to the nitrate is effected by Asp. aureus and Asp. batatae, but not by Asp. Oryze A.
(4) Neither nitrate nor nitrite is produced from the ammonium chloride by Asp. Oryzae A.
(5) The nitrite is assimilated selectively by all three species in presence of the nitrate, which is attacked only after the complete consumption of the former.
(6) The nitrite and the ammonium salt are consumed nearly at the same rate, although the former disappears somewhat earlier in the medium.
(7) Small quantities of ammonia are always formed in old cultures.
(8) Generally speaking, the nitrite may be regarded as an intermediate substance in the resorption of the nitrate by the moulds, especially by Asp. Oryzae A. The degree of the oxidation of the nitrite to the nitrate seems to vary in reference to the nature of the moulds.
The authors wish to express their heartiest thanks to Professor Dr. T. Takahashi, for encouragement given them in the present work.

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