kind and amount of available plant-food in the soil, 

 and the relative and absolute quantity of the various 

 soil-elements contained in the fruit raised upon it. The 

 absolute amount of the mineral constituents in plants 

 of the same variety may differ widely without chang- 

 ing the character of the plants; but a change in the 

 relative proportion of the various mineral constituents 

 almost always affects the quantity of some of the 

 organic constituents, such as starch, sugar, acids, etc. 

 This fact would seem to show that each of the various 

 mineral constituents has a special function in the 

 growth of plants. 'The more we learn of the specific 

 functions of each essential mineral constituent of 

 plants, the better will we be prepared to perfect our 

 system of manuring; to cultivate with a view of devel- 

 oping desirable qualities in the crops, and to counter- 

 act the serious influence of an abnormal composition 

 of the sap on the health of plants.' 



He further describes an experiment with currants 

 conducted at the College, in which these bushes, fertil- 

 ized in different ways and unfertilized, were compared. 

 From the analyses of the fruit it was evident that pot- 

 ash was the only ash constituent in which the soil was 

 deficient. The addition of this element in every in- 

 stance increased the percentage of potash in the fruit 

 as well as the amount of vegetable matter and sugar. 

 The colour of the berries was also improved. The in- 

 crease of potash in the currant was invariably accom- 

 panied by a corresponding decrease of phosphoric acid, 

 and of lime in particular, thus confirming his previous 

 observations with other fruits. The most striking 



