( iiArrKiJ XT.r. 



.MlNKKAl- XT'THIKNT MATEIUALS. 



J5 228. Alkalis. 



A GLANCE tliroii^'li the existing unalvti-iil <latu conferiiinfjj the 

 ash constituents of fungi (.see for example the luindlMjok by 

 J. KuMii ( \.)> will sodii ii-Vf.il tliiit thechief of these eoiistitvients 

 Hie phosphoric acid mul potash. The latter sel<l<»iii foiius less 

 than «)ne (|uarter, ami is generally about one half of the total 

 weight of ash, sometimes even rather more ; the ash of trulfles, 

 for instil nee. according to an analysis V>y I^iKitic (II.). contains 

 54.5 per cent, of K.,0 an<l 33.0 pel- cent, itf l\,Or^. From this 

 circumsttvnce alone it may be concluded that, as has already 

 been placed beyond iloubt in the ca^e of green plants, potassium 

 is also of importance to fungi. The first exj)eriment made in 

 order to clear up this (juestion was instituted by N.kceli (IV.), 

 and the results obtained led this worker to a.ssume that potas- 

 sium is so far non-csst-ntial t<» the growth of fungi that it can 

 bo replaced by rubidium or caesium; but that one or otln > ..f 

 the.se three must invariaMy be present. 



With regard to ca-sium, all sub.sef|uent investigators, how- 

 ever, agree that this met-al is unsuitable for replacing pot;issium 

 for the purpose in (piestion. InstJiiices of this are furnishetl bv 

 S. W'lMHiUAnsKY (XI.) in his culture experiments with Mi/ru- 

 (I'-niiii rini : W. Hkxecke (II.) in the case of I'' itirilltum ijhiurnm 

 and Aspenjillus ///_//'•;•; and sub.setptently by E. (Jue.nthek (I.) 

 for Miicor cori/mhifW, Jihi^ojnis ui'ji iraiiJ^, and Ii(>fri/fi.< riturea. 



Opinions are divided as to the suitability of rubi<lium for 

 replacing potassium. An allirmative result was furnislanl by 

 O. LoKw's ( V 1 1 . 1 tulture exj»eriments with a sjiecies of J'rniril- 

 Hum, and by Winogradsky with the lilm fungi alreadv men- 

 tioned. On the other hand, in th«> experiments of W. Henej'KE 

 (II.) potassium was found replaceable by tiiis allied met^il. but 

 only in cases where mt>rely vegetative development was in (pies- 

 tion. Finally, the experiments of E. (irEXTUEii (1.) furnished 

 no uniform results: the cultivation in solutions containing rubi- 

 dium, but nt> potassium, being succe>sful in the avse of liotriiti^ 

 cinerea, but not so with I{/ii:.'>})us ui(fnraiitt. Now, in oitK'r to 

 rightly appreciate these results it will be neces,s;iry to b»'ar in 

 mind the great dilliculty experienced in completelv freeing the 



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