Meyen’s Report for 1839 on Physiological Botany. 273 
matter, that the quantity necessary for their second budding 
is wanting. The physiologists have until now explained this 
well-known phznomenon quite differently, and had the 
author examined accurately with the microscope such bulbs 
as have once flowered, he would have noticed in them a great 
loss of starch and gum, and in their stead a large quantity of 
crystals. Indeed the growth of many plants which hang in 
the free air, e. g. the Arideea, Sedum Telephium, &c., is said 
according to the author’s view to be caused by mineral sub- 
stances, which are deposited on the leaves as dust, partly dis- 
solved by means of carbonic acid in the moisture of the room, 
and are then absorbed by the leaves. But here it is not dif- 
ficult to see that he applies everything to defend his hypo- 
thesis, which goes through the whole of this, in other respects, 
valuable work ; indeed, in some cases, where it is not at all 
necessary, e. g. in the last-mentioned; for we know already 
for certain, that such plants as grow in the air or in distilled 
water, consume their own reserves of nourishment, which are 
often very considerable. 
We consider also not only as a perfectly improved hypo- 
thesis, that which the author says concerning the formation 
of organic bodies in plants, but we believe that in the present 
state of Vegetable Chemistry we dare not propose such views. 
Plants, namely, are said to form their organic bodies out of 
the inorganic matters which they receive from the soil or the 
atmosphere by the assistance of light, heat, electricity and 
water, in a manner which remains to us for ever incompre- 
hensible. Such general doctrines as, “ Plants organize inor- 
ganic matters, and animals vitalize the already organized vege- 
table matters,” are indeed very attractive, but, as I believe, 
perfectly undemonstrated. Physiology teaches us that plants 
absorb all substances which are offered to them in a suffi- 
ciently fluid state, and if these substances act as poisons the ~ 
plants die; but the author inculcates in this respect the 
following, quite improved, doctrine. Minerals, as lead, arsenic, 
copper, selenium, &c., are without exception hurtful to plants, 
they injure however one more and the other less; which is ex- 
plicable by the fact, that the one plant more than the other, has 
the power of rejecting matters not belonging to its chemical 
composition, or if it has already taken them up, of ejecting 
them again, and this excretion takes place not only by means 
of the roots but also by means of the leaves, and these latter 
die partly thereby generally at the extremities. As an ex- 
ample to prove the latter statement very clearly, Sprengel 
states, that when a plant of barley a foot high is watered 
with a small quantity of a solution of a lead or copper salt, the 
Ann. & Mag. Nat. Hist. Dec. 1840. T 
