THE VEGETABLE CELL. 79 



plant wMcli stands in a fruitfal garden &oil, cannot owe more 

 than l-20th of its weight to the absorption of organic sub- 

 stances ("Recherches/' 268). An abundance of .experiments which 

 have been made by the greatest variety of observers, have 

 shewn that plants grown in sand which has been heated to red- 

 ness, in metallic oxides, frc, all organic substances being excluded, 

 exhibit growth, stunted though it be, and in many cases form 

 flowers and fruit. It is not requisite to demonstrate more 

 minutely how these circumstances shew the total error of the 

 view, supported, indeed, less by vegetable physiologists than by 

 agriculturists and foresters, that plants subsist solely on the 

 mouldering remains of former plants and animals. 



But on the other hand, it is not yet proved, 1, that all plants 

 possess the power of living upon inorganic substances, and 2, 

 that the inorganic substances are the sole food of plants ; that 

 the organic substances of humous onlj^ furnish a contribution to 

 the food of plants, in so far as they are separated into inorganic 

 substances by decomposition. This theory which, set up by 

 Ingenhouss, has found its most active supporter of late years in 

 Liebig, must in its one-sidedness be rejected in just the same 

 way as the opposite. 



In the first place, it is opposed by the no small number of para- 

 sitic plants, which are capable of using for food the sap of living 

 plants, and indeed, in very many cases, only the sap of a particular 

 one, or at all events of very nearly allied plants. A very large 

 portion of the parasites (the Loranthacese) agree with common 

 plants fully in their habit, colour, &c., another portion consist, on 

 the contrary, of leafless plants not of a green colour, which bear 

 the same relation to the plants which feed them, as the flowers 

 and fruit of other plants do to their vegetative oi'gans. 



In the second place, there exists a very large number of plants, 

 which in part resemble parasites in their exterior and in the 

 want of the green colom^, in part possess the usual aspect, and 

 which derive their nourishment only from vegetable or animal 

 substances in a state of decomposition. To these belong, besides 

 the numerous class of the Fungi, many Orchideas, bog-plants, &c. 



Thirdly, the majority of other plants exhibit a stunted growth 

 when raised in soil totally deprived of organic substances. In 

 this respect, however, as the experience of agriculturists and 

 foresters has proved, different plants manifest extraordinarily 

 different necessities. While one plant, such as the fir, buck- 

 wheat, Spergula, Sarothamus^ Erica, &c., flourish in a soil which 

 contains only traces of organic substances, others, like the Cereals, 

 require for their vigorous growth, a more or less abundant admix- 

 ture of mouldering substances with the earth. 



These circumstances indicate that dififerent plants have a dif- 

 ferent behaviour in regard to their nutrition ; that ^ in some 

 the power of living upon inorganic substances prevails, while 



