Proceedings of the Farmer^ Club. 187 



members, of some rather crude notions on the subject of the circu- 

 lation of sap in plants, our ex-President remarked that he thought 

 it one of those subjects about which little is known, and upon 

 which the light of scientific investigation should be brought to 

 bear. Now, nature acts by general laws, and our knowledge of 

 nature is our knowledge of these laws, which are as universal and 

 iiivai'iable as that law by which a stone when not supported falls to 

 the ground. Agriculture is one of the oldest of human employ- 

 ments, and the organism, functions and component parts of plants, 

 have of necessity been subjected to the interested observation of 

 man from the first, and it would be strange indeed if the most 

 prominent and noticeable vital action in plants had remained unob- 

 served and the laws governing it uninvestigated and undiscovered. 

 The cu'culatiou of sap in plants has not so remained unobserved or 

 uninvestigated, and writers upon botany and vegetable physiology, 

 from those authors of the earliest antiquity, of whose works only 

 fragments are now extant, to those of the present day, say to us in 

 the words of the Eoman scholar, ' why waste your time, when the 

 work is done to your hands?' The work of reinvention or redis- 

 covery is slow and difficult as well as superfluous. I propose, 

 therefore, to do little more than to collate a few of the established 

 facts in regard to the circulation of the sap, and the offices which 

 the sap performs in the growth of the plant. And first, what is 

 sap? Webster defines it as the juice of plants, especially the 

 ascending and descending juices essential to nutrition, but for our 

 purposes, we need a fuller definition, one showing its composition; 

 and it may, therefore, be defined as a thin watery fluid, composed 

 of water holding in solution those materials necessary for the 

 growth of a vegetable organism, to wit: salts, hydro-carbons and 

 azotized substances. Water being the medium in which these ele- 

 ments, so indispensable to the growth of plants, are dissolved, and 

 their introduction even, into the substance of the plant and passage 

 through its tissues rendered possible, would seem to be a most 

 important substance in vegetable economy, if not absolutely essen- 

 tial to the life of plants. Its composition is well known, two 

 measures of hydrogen to one of oxygen, or in weight 88.9 parts 

 oxygen to 11.1 parts hydrogen, and it is chiefly taken up by the 

 roots, embedded as they are in the moist earth, although it is also 

 absorbed by the leaves from the atmosphere, which always pos- 

 sesses more or less humidity. The salts, then, held in solution by 

 water, are freely absorbed by the spongioles with which the ter- 



