The Phosphates of America. 17 



CHAPTER II. 



PHOSPHATES AND THEIR ASSIMILABILITY. 



Ix the spring-time phosphates are found in noteworthy quanti- 

 ties in young organs of plants, especially in the leaves, but the 

 quantity gradually diminishes as the plant approaches maturity, 

 until when the blossoms appear the phosphates are found to have 

 entirely quitted the leaves and accumulated in the seeds. This is 

 the cause of that peculiar effect, which has long puzzled farmers, 

 that fodder cut and brought in after the period of maturity proves 

 to be much less nourishing to the cattle than that cut before this 

 period has arrived. 



It is worthy of note that in every instance this displacement of 

 the phosphates is accompanied by an equal displacement of the 

 nitrogen, and all those who have made successive analyses of grains 

 in different stages of maturity, must have been struck by the regu- 

 lar parallel manner in which the quantities of both have progres- 

 sively augmented. 



Mr. Corenwinder, alluding to this migration of phosphorus in 

 vegetables, remarks : 



"It has long been known that young buds are rich in nitrog- 

 enous matters, which are always accompanied by a relatively 

 considerable portion of phosphorus, and there is no doubt that 

 these two elements are united in the vegetable kingdom according 

 to some mode of combination which is yet a mystery." 



And Mr. Boussingault, writing upon the same subject, says : 



" We perceive a certain constant relation between the propor- 

 tions of nitrogen and phosphoric acid contained in foods, those 

 being richest in the latter element which contain most nitrogen. 

 This would appear to indicate that in the vegetable organization 

 phosphates particularly cling to the nitrogenous principles, and that 

 they follow the latter into the organization of animals." 



The absolute necessity for the presence of phosphoric acid in 

 the soil needs no further discussion. It is admitted on all hands 

 that in its absence, vegetation, even when abundantly supplied 1 

 with nitrogen and all other necessary elements, must come to a 

 standstill. 



