FERTILIZERS IN FRUIT CULTURE. 441 



l)ccn noticed without having affected the quantity of some of 

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



The fact that the essential mineral constituents (potassa, 

 calcium, magnesium, iron and phosphorus) of our farm 

 plants cannot replace each other beyond a certain extent in 

 the vegetable economy without endangering their life, points 

 towards a specific function of each of them in the growth of 

 these plants. AVe have learned, by experimental observa- 

 tion, what elements are indispensable for a healthy growth, 

 and a successful reproduction of these plants. It remains 

 for us, then, to ascertain the particular function of each of 

 the above elements in the life of plants. The more we 

 learn of the specific functions of each essential mineral con- 

 stituent of plants, the better will we be prepared to perfect 

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

 oping desirable cjualities in the crops, and to counteract the 

 serious influences of an abnormal composition of the sap, 

 on the life of plants. 



To secure suitable material for an examination in the 

 above-mentioned direction, five experimental plats were set 

 apart for that purpose in 1875. They were planted under 

 the direction of Prof. Maynard, with strawberries, rasp- 

 berries, currants and blackberries, besides cherry, plum, 

 pear and apple trees. Four of these plats received, annu- 

 ally, a certain kind and amount of chemical manure (see 

 currant exi^eriments), Avhile one plat received no manure. 

 Upon each plat were planted the same kind and variety of 

 fruits. Some interesting observations made on grape-vines 

 and strawberries have been already published in the annual 

 reports of the college, in the report of the Massachusetts 

 State Board of Agriculture for 1879, and elsewhere. A 

 brief description of experiments with healthy peach trees, 

 and with trees suffering Avith " the yellows," has been pub- 

 lished in the report of the INIassachusctts Horticultural So- 

 ciety, and of the State Board of Agriculture for 1882. 

 A more detailed description of these experiments, in partic- 

 ular, will be found in the annual report of the Board of 

 Control of the State Experiment Station, for 1883. The 

 experiments with currants, below described, furnish an in- 

 teresting addition to previous observations. 



