390 Physiologie. — Algae. 



of dhurrin between leaves and stalks, there being a proportionately 

 smaller amount in the thick, heavy stalks than in the slender ones. 



There is no consistent daily Variation in the amount of dhur- 

 rin, which argues against the functioning of this glucosid as a food 

 storage. 



Of the two varieties used in this experiment, the Southern 

 Cane in every plot but one had a higher content of hydrocyanic 

 acid than the Early Amber. Varietal difference is probably of more 

 weight in determining the amount of hydrocyanic acid in sorghum 

 than are the conditions of growth. M. J. Sirks (Wageningen). 



Wyatt, F. A., Influence of calcium and magnesium com' 

 pounds on plant growth. (Journ. agr. Research Washington- 

 VI. p. 589-619. 1916.J 



From the results of the writers experiments may be concluded: 



Wheat, soybeans, alfaifa and cowpeas grew normally either in 

 96 per cent of dolomite and '4 per cent sand, 100 per cent of mag- 

 nesium limestone, or in sand 7 per cent of magnesite. 



Dolomite up to 40 per cent proved beneficial to plant growth. 

 These results indicate that dolomite and magnesian limestone will 

 not be detrimental as applied in agricultural practices. 



Applications of prepared magnesium carbonate up to 0.7 per 

 cent caused no injury in brown silt loam, but 0.35 per cent pre- 

 vented the growth of all plants lested in sand. 



The crop yields and the ratio of calcium to magnesium in the 

 plants bear no direct relation to the ratio in the natural carbonates 

 applied. 



Different ratios of calcium to magnesium within rather wide 

 limits produced no marked differences in yields. 



Increasing the size of applications increased the calcium and 

 magnesium content of plants. 



A tolerance of calcium and magnesium occurred in all varieties 

 of plants grown. With approximately identical yields, wheat straw 

 grown in sand, brown silt loam, dolomite, and soil containing 35 

 per cent of magnesite showed calcium contents varying between 

 0.165 per cent and 0.547 per cent and magnesium contents varying 

 between 0.132 per cent and 0.955 per cent. 



Acid extractions failed to remove all the calcium and magne- 

 sium from the sand. There remained after the various extractions 

 from 768 to 892 mgm. of calcium and from 540 to 960 mgm. of 

 magnesium per 6.000 gm. of sand. 



The plants possessed a decided ability to obtain calcium and 

 magnesium from sand extracted with strong hydrochloric acid, as 

 born out by the following example: Three crops of alfaifa removed 

 from acid extracted sand 164.43 mgm. more calcium and 90.4 mgm. 

 more magnesium than was contained in seeds similar to those 

 planted. M, J. Sirks (Wageningen). 



Lohmann, H., Ueber Coccolithophoriden. (Vortrag Deutsch. 

 Zool. Ges. 23. Jahresversamml. Bremen. 1913.) 



Die Zahl der Geissein ist systematisch ohne Belang. Eine Ta- 

 belle zeigt die vertikale Verteilung der wichtigsten Gattungen. Einige 

 interessante Formen werden besprochen: das Protozoon Heydeckia 

 barkowi, das sich mit Trehmaliten umgibt, Heiiniella excentrica, die 



