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 phenomenon 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 JEridece, 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 



