Lo 
1887] Comparative Chemistry of Higher and Lower Plants. 723 
tainly seem to possess greater chemical skill than a higher race 
of beings exhibit in their laboratories. Some few of this higher 
race are “ going to take lessons” how to construct proteids and 
carbo-hydrates as we are told our now automatic cousins were 
once taught to do; though man fails to consider that it may be 
a lost art, and the secret has died with the plants in a “ catage- 
netic” decline. 
All plants and their products are composed. of two general 
classes of compounds,—volatile and fixed. The former, on in- 
cineration of the plant, is transformed into gases, leaving the 
_last as so-called ash-constituents. 
I will very briefly refer to the sources of the substances which 
go to the building of the plant structure. Green plants derive 
their carbon from the carbon dioxide of the atmosphere, and 
even from complex organic compounds, since Darwin’ has 
shown that insectivorous plants, by means of their modified 
leaves, are able to absorb flies and other small insects. 
Plants which do not contain chlorophyll, as fungi, take their 
carbon from complex compounds of decaying organic matter. 
. Not only do all the so-called organic compounds of plants con- 
tain carbon, but it is found also in the form of carbonates.” 
Hydrogen is absorbed by all plants in the form of water, or 
ammonia and its compounds, or in complex substances, as 
Mentioned above, Oxygen is taken up by plants free or in 
combination in water or in salts, and there are six possible 
Sources of nitrogen supply; but I will not delay by going into 
this subject.3 
- Sulphur and phosphorus are constituents of proteids, and are 
derived from inorganic compounds. In addition to these the 
elements essential to the nutrition and maintenance of the life 
of all plants are potassium, calcium, magnesium, iron in the case 
; of green plants, its absence producing the condition of etiola- - 
tion; and, in certain cases, chlorine. Silicon, fluorine, manga- 
_ ‘Rese, sodium, lithium, rubidium, cæsium, barium, strontium, 
_ aluminium, zinc, copper, arsenic, titanium, iodine, and bromine 
- have also been found among the ash-ingredients of certain 
* Insectivorous Plants. * Adm Phys, et Chim., Berthelot. 
The Economical Aspect of Agr. Chem., by H. W. Wiley, Proc. A. A. A. S., 
= XXXyv,, 1886, ; ; 
at, 
