I. AGRICULTURE AND RURAL ECONOMY. 367 



the stack produced, by means of which the heat is speedily 

 carried oft* without any injury to the stack. Hooks may be 

 attached to the tip of the instrument by which small samples 

 of the central part of the stack can be brought out. 9 O, 

 February -,1872,19. 



SOURCE OF NITROGEN IN THE SOIL. 



According to Deherain, the sources of the nitrogen of the 

 soil, as at present recognized, are insufficient to account for 

 the 'amount of nitrogen which the soils contain, and he tries 

 to prove, by certain experiments, that the free nitrogen of the 

 atmosphere is brought into combination during the oxidation 

 of the organic matter of the soil. 21 A, February, 1872, 164. 



FUNCTION OF POTASSIUM IN SOILS. 



According to Nobbe, the presence of potassium in soils is 

 necessary in order to enable the chlorophyll grains of the 

 leaves to form starch ; sodium and lithium being unable to 

 replace potassium in this function the latter, indeed, being 

 actually injurious. He has also ascertained that the different 

 combinations of potassium vary very much in their value, the 

 chloride being by far the most efficacious. 21 A, February, 

 1872,167. 



GRAFTING WAX. 



The gardeners of Metz use a grafting wax which is con- 

 sidered of very excellent quality. It is prepared by melting 

 together two parts of white and one of black pitch, and stir- 

 ring the mixture thoroughly during the operation. Close by 

 the vessel filled with the melted wax is placed a basin con- 

 taining cold water, into which the hands are immersed, and 

 then as much of the wax taken from the melted mass as is 

 necessary for each particular application in grafting. 6 (7, 1., 

 1872,87. 



PHYSIOLOGY OF GRAFTING. 



Mr. Gceppert, in Silesia, gives results of some observations 

 in reference to tree-grafting substantially as follows : Upon 

 the vertical surface of the stock a tissue of parenchyma is de- 

 veloped, proceeding from the medullary rays, which enters 

 into intimate connection with that of the scion. At the same 



