8 INANITION AND MALNUTRITION 



" It appears that a certain quantity of Ca ions must be present in the medium 

 for the maintenance of the chemical and functional integrity of the deeper 

 King living parts of the cells of absorbing roots of higher green plants . . . 

 When this necessary minimal supply of Ca ions is lacking ... the function of 

 absorption is upset and a more or less marked leaching of ions from the plant 

 follows. In the absence of this necessary minimum of Ca, the soil solution or 

 culture solution may be rich in all other required ions, but these are useless 

 to the plant. They are unabsorbable." 



Von Liebig ('76) stated that calcium is doubtless necessary for cellulose 

 formation. Boehm ('75) in Phaseolus vulgaris, v. Raumer ('83) in Phaseolus 

 multiflorus, and Molisch ('95) in Spirogyra noted that a calcium deficit inter- 

 feres with the formation of new cellulose walls after cell-division. Reed ('07) 

 likewise noted that in Spirogyra and roots of Zea mais kept in solutions without 

 calcium salts, although nuclei divide mitotically, new cell septa are formed 

 imperfectly or not at all. After two months in Ca-free solutions, most of the 

 Spirogyra cells were found dead and those alive markedly degenerated. He 

 states, however, that some investigators (Bruch '02) have found calcium unnec- 

 essary for nutriment in fungi and lower algae, and even toxic in some cases; but 

 all agree that seedlings in calcium-deficient solutions usually develop small 

 leaves. Reed also found that in Spirogyra, Zygnema and Vaucheria, calcium 

 appears necessary for the growth and activity of chlorophyll and chloroplasts 

 (in agreement with Bokorny '95 and Loew '92); perhaps serving also as an 

 antidote to the bad effects of magnesium, oxalic acid, etc. He further observed 

 that spores of Gymnogramme sulphur ea, cultivated in calcium-free solutions, 

 developed prothallia in which antheridia were produced in large numbers, but 

 archegonia were absent. Controls were normal. In certain mosses (Atri- 

 chum), he noted that the spores fail to germinate in calcium-free solutions, 

 although a retarded development (with peculiar moniliform cells) occurs when 

 the calcium is replaced by sodium. Palladin ('18) emphasized the importance 

 of calcium for normal leaf development of plants. In the development of the 

 oat plant, Dickson ('18) found that a deficiency of calcium increased the general 

 vigor of growth, lengthened the period of development and increased the total 

 dry weight of the plant. The grain production was lowered, however, the ratio 

 of grain to straw and the weight of the individual kernels being decreased. 



POTASSIUM DEFICIENCY 



According to Reed ('07), de Saussure, in 1804, established the necessity of 

 potassium for the growth of terrestrial plants, which has been confirmed by 

 Nobbe ('71) and many later investigators. Dickson ('18) found that in the oat 

 plant a deficiency of potassium in the nutrient solution causes a decrease in the 

 general vigor of growth, a shortened period of development and a decrease in 

 the total dry weight of the plant. The grain production is also lowered, 

 although the ratio of grain to straw is increased and the weight of the individual 

 kernels greater. 



Cytological effects of potassium deficiency upon algae (chiefly Spirogyra) 

 were noted by Bokorny ('92). He found the chains of cells broken up into small 



