44 



containing magnesia but no lime, although larger than the others/ pro- 

 duced only a few short hairs. The lack of lime in these roots was felt 

 especially in the epidermis, the interior parts being able to draw a 

 sufficient amount of lime from the stem. Indeed, a microcheraical test 

 showed the presence of lime in the ash of these roots, gypsum needles 

 forming when treated with a little sulphuric acid. 



The extraordinary effects of lime salts on the development of root 

 hairs is of special interest, as it furnishes the key to the observation of 

 Wolff that the potassium and ammonium salts of the soil are absorbed 

 in increased quantities by plants after manuring with lime salts. 



LIFE WITHOUT LIME SALTS. 



While lime salts are indispensable for animals. Phanerogams, and 

 higher algt^, tbey are not so in the case of bacteria, fungi, and lower algae. 

 Thus far no investigations relating to the higher fungi have been made 

 in this regard. The occurrence of lime in the ash of yeast or of 

 tubercle bacilli ^ must be regarded as merely accidental. It was first 

 observed by Adolph Mayer that for yeast magnesia is of greater impor- 

 tance than is lime. Later the writer proved that yeast and bacteria can 

 do without lime entirely, ' and Molisch has observed that this is also true 

 of mold fungi.^ It has been observed, on the other hand, that in cer- 

 tain cases the presence of lime promotes the action of fungi, but this is 

 very probably due only to a secondary effect. Thus, the nitrification 

 in soils is enhanced by calcium carbonate, and, according to Thaxter 

 and Wheeler,' the scab of potatoes and of sugar beets is increased by 

 liming the soil. Recently Laurent" reported that certain bacteria. 

 Bacillus coli communis and B. fluorescens putidus, can attack potatoes 

 in soils which have been strongly limed. He believes that by 

 this means the power of resistance of these plants is diminished so 

 much that the microbes named can commence their parasitic life, and 



1 These roots were 4.1 cm. long, while those in culture solutions without magnesia 

 were only 3.2 cm. long. The composition of the complete culture solution in the 



above case was as follows: 



Per mill«. 



Monopotassium phosphate 0- ^ 



Potassium nitrate • ^ 



Sodium sulphate 



K 



Calcium nitrate 



o 

 Magnesium sulphate 



Ferrous sulphate Trace. 



^According to de Schweinitz and Dorsett (Centralbl. f. Bakt., No. 23, 1898), the 

 phosphates of sodium, calcium, and magnesium predominate in this ash over that 

 of potassium, while the reverse is true in the ash of yeast. 



3 Flora, 1892, pp. 374 and 390. 



•"Ber. Wien Akad., 1894, Vol. CIII. 



eStorer, Relation of Agriculture, Vol. II, p. 546. 



6Ann. de I'Inatitut Pasteur, 1899, Vol. XIII, p. 1. 



