physiologically considered. 305 



taken to form a sufficient drainage at the bottom, and that the 

 earth is not too closely pressed down. It should also be borne 

 in mind that shallow pots are preferable to deep ones. 



In the first number of the Garten Zeitung for 184-0, charcoal 

 ashes were recommended as the best medium for striking cut- 

 tings. We do not wish to deny the beneficial influence of this 

 substance on the vegetation of many plants ; and we think that 

 the charcoal ashes impregnated with humus, or as M. Lucas 

 says, ashes dissolved by the air, in many cases operate favour- 

 ably on the developement of cuttings, and that charcoal will act 

 an important part in propagation, particularly when experiments 

 have been more generally made. The theory grounded upon 

 these experiments by Dr. H. Buchner, sen., on which he proposes 

 to found a system of curing sickly plants, we can, however, in 

 many particulars, by no means support. It is not our intention 

 to refute this treatise in detail, we leave that to chemists : for we 

 can only admit that charcoal has an indirect influence on the 

 vegetation of plants; for the dissolution of charcoal itself, and 

 the formation of nourishment for plants, verge on impossibility, 

 as it is well known that charcoal is not dissolvable in water, 

 spirits of wine, oils, or alkalies, nor does it undergo a change in 

 the usual temperature of the air and water. The opposite results 

 of chemical annalyses may be explained by supposing that the 

 charcoal ashes, which had been previously used, had imbibed much 

 extraneous matter from the water poured upon them, and from 

 the atmospheric air. The absorption of the atmospheric air, 

 as oxygen gas, nitrogen gas, carbonic acid, hydrogen, &c, is 

 certainly one of the properties of charcoal, but the dissolution 

 of these gases only takes place at + 80° Reaum., so that it does 

 not appear that they can be transmitted to the plant by the char- 

 coal. We are the more strengthened in this opinion, when we 

 observe in other cases how charcoal mixed with earth for hydran- 

 geas produces the very contrary effect, and changes the red co- 

 lour of these flowers into blue, by withdrawing the acid. 



When used for cuttings according to M. Lucas's directions, it 

 operates first conservatively, as by its antiseptic powers it pre- 

 vents decay, and consequently may be employed with great ad- 

 vantage with Cacti, and other plants subject to damp off. Besides, 

 the water given to the cuttings in charcoal ashes is as chemicallv 

 pure as possible, as the charcoal partly withdraws the particles 

 of humus from them ; or it contains but very few of these par- 

 ticles, when the ashes have been sufficiently saturated with re- 

 solvable gases. The cutting is hereby forced to make use of the 

 reserved nourishment laid up in its interior, and the process of 

 assimilation in many cases takes place sooner, and consequently 

 the formation of roots also. The greater luxuriance and stronger 

 growth of the roots which M. Lucas observed may be connected 

 3d Ser.— 1842. VI. x 



