It was confirmed that mice bearing many transplantable tumors are infected with a virus-like agent which causes a 5- to 10-fold elevation in the plasma lactic dehydrogenase activity of infected mice without tumors. The agent is non-identical with the polyoma virus and without effect on adult rats and hamsters. Maximum titers of 109 to 1010 ID50 per ml of plasma were observed within 36 hours after infection. Subsequently the titer decreased to 105 to 107 ID50 per ml and remained constant thereafter. The plasma lactic dehydrogenase reached maximum activity about 96 hours after infection and remained elevated indefinitely. The virus was present in feces and in a variety of tissues and organs in relatively high concentrations. Liver and spleen yielded the highest titers.Five electrophoretically distinct forms (isozymes) of lactic dehydrogenase were separated from mouse tissues. Infection of mice resulted in an increase of the slowest migrating isozyme in the plasma. Liver, spleen, and erythrocytes were each found to contain only this isozyme while other tissues and organs contained mixtures of lactic dehydrogenase isozymes. The plasma of tumor-bearing mice contained more of the slowest migrating isozyme than infected mice without tumors.

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A simple, nonaseptic, low-cost process for the conversion of cassava, a starchy tropical root crop, into microbial protein for use as animal feed was sought. Screening tests culminated in the isolation of a thermotolerant, amylase-producing mold, designated I-21, which was identified asAspergillus fumigatus. The optimum pH for protein synthesis was 3.5, but the optimum temperature was less than the desired temperature (545 C) required for a nonaseptic fermentation. A. fumigatus 1-21 and its asporogenous mutant I-21A grew equally well in a medium prepared from whole cassava roots with a mean protein doubling time at 45 C and pH 3.5 of 3.5 h. In batch culture, approximately 4% carbohydrate, supplied as whole cassava, could be fermented in 20 h, giving a final yield of 24 g ofdry product, containing 36.9% crude protein, per liter. The conversion ofcarbohydrate used to crude protein was 22.1%. When determined as amino acids, the protein content of the product, which contained cassava bark and other unfermented residues, was 27.1%. With urea as the nitrogen source, no pH control was necessary. Preliminary data indicated that medium prepared from whole cassava roots was inhibitory to the mold unless the cassava pulp was heated to 70 C immediately after being ground. Heating to 70 C was required to gelatinize the starch and permit its complete utilization.

Two strains of Strepto?izyces scabies and a Strepto~i~yces sp., strain T12, h a w been sti~died for hpphal anastomosis ancl its cytological consequences. The presence of multiple short hyphal bridgcs between neighboring hpphae and the absence of dcrnonstrable cell walls or ~ncmbranes a t the points of contact are presented as cvidence for anastomosis. The formation of "initial cells", as a result of hyplial fusion, \\.as not obser\led. Two types of s\\rollen boclies, decply stained by the acid-Giemsa method, were noted. Onc type, identified as the residue of the parent spore, passcd t h r o~~g h a stage during,w!lich it did not stain by this lncthod but s~~bsequently became highly c h r o m a t~~l~c .The s c c o~~d type was aln.ays terminal and developed concurrently with or subsequent to "secondary mycelium". Aerial hpphae \\.ere observed to arise directly from "prilnary mycelium" in S . scabies. Hyphac wit11 cytological characteristics intermediate between primary and secondary types mere observed in Strepto~izyccs sp. T12. ' M a~~l i s c r i p t received J l~l y 4, 1956. Cor~triblitio~z frotrz the Departinent of Bacteriology, Olttario Agricult~~ral College, G l~e l p l~, Owtnrio. Tlze iitoestigatio~t was part of tAe progranz of tlze Outario Potato Scab IZesearclz Can. J. Microbiol. Downloaded from www.nrcresearchpress.com by UNIVERSITY OF MICHIGAN on 11/17/14 For personal use only. ?./I w e t l i~~g c~gelzl obtained from l l~e Allas Powder Co., H f i l~i z i~~g t o~~, Delawc~re, U.S.A. Yeasl exlracl, 3 . 0 gnt.; beef exlracl, I . 5 gnr..; peplone, 6 . 0 gnl.; gl.ucose, 1 . 0 g1rz.; disfilled aualer, 1000 ~1 . ; PI1 6 . 5 . Can. J. Microbiol. Downloaded from www.nrcresearchpress.com by UNIVERSITY OF MICHIGAN on 11/17/14 For personal use only.