No. 6. DEPARTMENT OF AGRICULTURE. 401 



function of lime in the plant, the similar bases, baryta and stomatic, 

 ©hould be capable of replacing it perfectly, since both form such 

 oxalates. It is true that Patterson (2) has found a distinct crop in- 

 crease to follow an application of baryta upon a soil profiting from 

 the use of lime; but this may be explained by the chemical action of 

 the baryta upon the soil, rather than in the plant. Loew (3) has 

 found in experiments with twigs of Tradescautia, that barium and 

 strontium salts are positively injurious when the quantity of lime 

 present falls below a certain minimum. 



In the bulletin previously mentioned, (4) I have brielly discussed 

 the evidence of the belief that lime is essential to formation of 

 cellulose, the substance of the plant's skeleton, and recorded the ob- 

 servation of Mayer and Cohn that beer-yeast, which builds about its 

 spherical body, a thin wall of cellulose, dies so without requiring the 

 aid of lime. It is now known that other lower organisms are capable 

 of performing all their normal functions without lime. Loew (5) 

 found this true of certain lower moulds, and confirmed the same ob- 

 servation made by H. Norisch, with reference to some of the algae. 

 He thinks that only when the plant reaches a rather high degree of 

 organization does lime become needful, and that this plant food is 

 intimately concerned in the making of albuminoid compounds that 

 go to form the nucleus and chlorophyll bodies of the plant, or in other 

 words, its centers of reproduction and assimilation. The same 

 writer, in conjunction with D. W. Nedy, had continued investigations 

 upon the subject. (6) They note that magnesium compounds though 

 essentia,l in limited quantity to plant formation, are poisonous to it 

 when in excess; but that the presence, at the same time, of a certain 

 proportion of lime entirely prevents this injury; that the proportion 

 o^ seven parts of lime in soluble combination to four of magnesia so 

 combined is sufficient for the best results; that an excess of lime 

 tends, however, to starve the plant. 



The practical suggestion from the latter hypothesis is that when- 

 ever there is likelihood of excessive magnesia consumption by the 

 plant, lime is a desirable fertilizer. Such cases occur in many soils 

 very rich in magnesia as compared with lime, and where the less con- 

 centrated potash salts, such as kainit, are used, which are also rich in 

 magnesium compounds. 



Whatever the explanation, it is found that most plants grow more 

 thriftily on a calcareous soil than on one deficient in this food; the 

 stems are stronger and stockier and the entire plant more vigorous. 

 F. Wohltman (7) recently observed its tendency to stiffen cereal 



(2) Bulletin 66, Md. Exp. Station. 



(3) Jahrpshincht t. Agrik.-Chem., 1S98, 203; Bulletin 18, Div. Veg., Physical and Patte., U. S. 

 Dept. Agrlc. 



(4) Bulletin 61, Pa. Dept. Agrlc, pp. 58-9. 



(5) Op. clt. supra. 



(6) Bulletin 1, Bureau of Plant Industry, U. S. Dept. of Agric. 



(7) Jahresbincht f. Agrik-Chem., 189S, 18S-9. 



26—6—1901 



