EXCIIKTION OF PLANTS. 



otluT substances, to matter useful to the /]frowth and existence of the plant ? It has 

 been inferred by ft oorresj)undcnt of the Horticulturist^ in the page ijuoted above, that 

 many of the deaths which are suj>posed to result from " sour soil " and " overwater- 

 inff," are rather caused by an accumulation of excrementitious discharges. Has there 

 been anything discovered by which to prove that this " sourness" is not what most 

 gardeners take it to be — the result of an acid ? I, and no doubt the majority of my 

 practical brethren, have frequently observed that the greater the amount of organic 

 matter in soil, the easier does it " sour." We are particularly anxious to avoid the 

 use of leaf mold in any other state than " well-rotted," on that account. An abund- 

 ance of water is favorable to the decomposition of organic matter ; and " soils contain 

 a peculiar acid analogous to bumic acid, produced during the decay of vegetable 

 matter, which is hurtful to the growth of plants." — {^Solhj. Bur. Chcm., par. 313.) 

 LiNDLEY himself, one of the advocates of the excrementitious doctrine, suggests that 

 " the subject has hitherto been so little investigated, that it is not safe, perhaps, to take 

 it as the basis of a theory." — {^Theory of Horticulture.) And since his time, IIen- 

 PREV, the most searching of modern physiologists, considers the theory as " entirely 

 without foundation." — [Hcnfrcy'^s Outlines of Veg. Pkys. I quote from memory.) 



Although there seems, then, to be no evidence that the excrements of plants have 

 the injurious effects on the soil they are charged with, the discussion of the subject 

 has been productive of good. It has caused attention to be called to the nature of 

 impoverished soils, and its causes, which must in the end produce knowledge which 

 will be of undoubted interest to the cultivator of the soil. 



[The question regarding the excretions of plants stands at the present moment 

 as unsettled and debateable as ever. Duiiamel, we believe, was the first to call 

 attention to it, being led to suspect excretions on account of the earth adhering to the 

 young roots, or spongioles of plants. Brugmans, Decandolle, tuid others, took it 

 up and collected a large number of facts (familiar to readers on this subject) bearing 

 upon the point and furnishing a sort of circumstantial evidence in favor of such a 

 theory. Macaire Prixsep, at the suggestion of Decanuolle, made a series of 

 experiments to test it, by growing a great variety of plants in phials of pure water ; 

 and the results were such as gave additional strength to the excretive doctrine, at the 

 time. But practical men were not satisfied with experiments conducted upon plants 

 in such unnatural conditions, and other experiments of a more reliable nature, subse- 

 quently conducted by some German phytologists, produced entirely opposite results. 

 The theory, therefore, has never been fully established, although we believe that a 

 majority of those who have given the subject attention regard it with a greater or less 

 degree of favor. For our own part, we do not wholly discard the doctrine. Wo 

 almost daily meet with cases in practice that persuade us that at least it is not unrea- 

 sonable. In turning up the soil in which certain plants have grown — the cabbage and 

 turnip tribe, for instance — we find peculiar odors escape. So in potting or shifting 

 house-plants, we find that different plants impregnate with different odors the soil in 

 they have grown. Tliis may or may not be due to the process of excretion. 



