IMPORTANCE DES COLLOIDES NATURELS INORGANIQUES. 369 
La bibliographie in extenso du sujet, jusqu'á 1905, se 
trouve dans mon article: Una nueva ciencia, la plasmogéne: 
sis. Boletín de la Secretaría de Instrucción Pública. TomoIV. 
p. 608-623, figs. 
in regard to the chemical composition of rice germ, L. BERNARDINI (4bs. 
in Chem. Ztg., 35 (1911), No. 48, p. 437). The phosphorus content of the 
entire rice seed was found to be 0.95 per cent, while in the embryo it was 6.2 
per cent. The greater portion of the phosphorus is phytin, that is, anhydro- 
oxydimethylene diphosphoric acid. The ash of the embryo besides containing 
the usual elements also contains silicic oxid, potassium, and magnesium. Si- 
licie acid has probably a greater physiological significance than has been hereto- 
fore attributed to it, A great similarity between the content of nitrogenuos 
substances and the composition of the ash in the embryo and that in the aleu- 
rone grains (layer) was noted. The magnesium oxid content of the embryo is 
1.39 and of the calcium oxid 0.27 per cent. 
The role of silica in the nutrition of plants, A. SPRECHER (Bul. Soc. Bot. 
Genéve, 2. ser., 3 (1911), No. 4, pp. 155-192, figs. 4. Experiments with 4vena 
sterilis grown in 4 culture solutions with and without silica are reported. 
The Knop-Pfeffer solution gave the best results. Thisis believed to be due 
to the slight acidity from the iron chlorid and potassium acid phosphate. The 
addition of silica from the solutions in general increased the dry weight as well 
as the important constituents, such as ash, proteid substance, crude fiber, and 
carbohydrates, although there was some variation in the proportion, due prob- 
ably to the different culture solutions. 
Where the same compounds were available silica was less abundant in 
the well grown plants than in those poorly developed. The percentage of min- 
neral salts absorbed by the plants diminished with the addition of silica, 
although the absolute ash became greater. In the lots without silica the plants 
contained greater amounts of lime, phosphoric acid, and iron in proportion 
to potash. 
Without affirming that itis necessary to plants, the author believes that 
silica has an important biological function in stimulating plants to greater 
growth, and that it probably plays the róle of maintaining a physio'ogical 
equilibrium in the nutritive solutions in the soil. 
A bibliography is appended. 
Mem. Soc. Alzate. 'T, 32 ( 1911—1912).—47. 
