ALKALIS. 43 



]{hi::(ijii(s iii</ri<-(tii,'', ami Jlotii/tis rotrrea. TIio rule tlieiofore 

 Htill liohl.s ^ij(j<l tiiiit xjtliuiu is of no a|i|>rucia1ilL' utility as ivpirJ* 

 tilt' nutrition of funj^i, and run be entirely ilisjienseil with. The 

 UiaxiuiuMi (juantities of the salts of this metal that can he pre- 

 sent in the nutrient solution without injury, have been deter- 

 mined hy E. (luenthei-, in the case of Hliizoj'us nit/nram, as 

 follows: NaCl. 12 per cent.; Na.,SO^+io iup, 26 per cent.; 

 uiul NaNf)^, 6 per ci-uf. 



With re^'anl to lithiiun, W . IUcnecke (111.) has shown — in 

 refut^ition of the contrary assunijition hy Nae^eli — that this 

 metal is not a foodstutf for fun<.M, althouju'li a strong stimulant. 

 When lithium sjilts were piest-nt in the nutrient solution it was 

 found that the conidia of Axj eriji/liix imji r did not {,'erminate, 

 and that no conidia were formed in the case of an uns|iecified 

 species of PfniriUiiiiii. The extent to which the various species 

 ure M-nsitive to the action of this metal must Uuctuate consider- 

 ably, since, whilst E. (SfEXTiiEU (L) found 0.05 per cent to be 

 the largest addition of lithium nitrate that Hhtiitjmt; nitjricans 

 coultl stmd and still continue to thrive, 11. M. KiriiAUDS (I.) was 

 able to observe that A}'/>'i</i//its iiii/n- gave a crop of ilouble the 

 usual size when the nutrient .solution of sjiccharose and mineral 

 salts was tre^ited with an addition (»f 0.3 to 0.5 percent, of lithium 

 chloride. 



§ 229. Metals of the Alkaline Earths. 



According to N.EtiEi.i (IV.) magnesium is non-es.sential for 

 the development of fungi when the latter have at disposal one 

 of the three alkaline earths: strontium, barium, or calciiun. 

 The a>-<umption that fungi can grow witht»ut magne.>ium has, 

 however, Ihh'U disproved by WlNo»;u.\USKV (Xi.). who showed 

 that the latti'r is iiulispen.sjible for the development of Mi/ro- 

 ■/■ III, I riiii. The siime results were obtained bv Adolf Maver 

 in culture experinu-nts with beer yeast; by 11. Moi>iscii (11.) ami 

 W. iU:.N'EC'KE (1.) with PenirU/ium tjlawnin aiul As]terijilliis tiiijrr ; 

 and by E. (!t EXTllEK (1.) with Mnrur ron/iiihi/er, lihizopua niijri- 



tins, and Jinfri/iis ciinnn. Mow .sensitive and responsive the 

 tungi are to a .small adtlition of magnesium is evident from the 

 ()bservation rect)r«led by Henecke (1 1 1.) as to the consiilei-able 

 dilTerence in tlevidopment exhibited bv two, otherwise «'<pial, 

 speciuien.s, the one grown witln)ut magnesium and the other in 



I medium containing 0.0025 "'r.'- "^'^ crystalline magne.-sium sul- 

 phate per 25 e.c. 8imilarly. E. Gl7EJ<TnEK (1.) a.scertjiiniHl, in 

 theca.se of magnesium sulphate, (MgS()^ + 7 a(j ), that a mini- 

 mum addition of o.oo^ mg. was nece.>i.>iarv to induce a sowin;: of 

 I{/ii:opus ni(jrit'ans to grow at all. 



In refutation of an e.ulier assumption bv Sestini, it has been 

 shown by II. Mol.iscii (II.) and W. Hknecke ( I.), and after- 



