82 
GARDENING AS A SCIENCE. 
or grow fat upon soda water. Living bodies, whether vegetable or animal, can 
only be nourished and developed by organic matter. Now, crude sap may very 
possibly not contain a single particle of organic matter. The mystery is explained 
by the fact which Physiological Botany has ascertained, that plants are endowed 
with the peculiar faculty of preparing organic matter for themselves, out of the 
materials which the crude sap contains," 
Crude sap is generally said to consist of water, holding in solution a quantity 
of carbonic acid derived from the decomposition of decaying manure or vegetable 
matter in the soil ; but the notion is as crude and ill-digested itself, as thing can 
possibly bOo In fact, we know not what this sap is, or how it can be collected. 
If we take either the oozings of the vine (the subject best at command), at early 
spring, when every recently pruned shoot emits at certain recurrent periods of the 
day, drops of apparently limpid water ; or collect the sap of the birch-tree, by 
boring into its stem ; we obtain sap, doubtless, but always more or less blended with 
the prepared juices of the stem and bark. Assuming however, the droppings of 
the vine as a type, we find a liquid almost insipid, but which — so far as our test of 
lime-water can determine — yields no trace of carbonic acid, but gives a very per- 
ceptible deposition of lime, by adding a minute particle of oxalic acid to the sap. 
This acid possesses an affinity for lime, so strong, that a union with it takes place 
when the proportions of each are very minute, and diffused tlirough a considerable 
volume of water. 
Crude sap, therefore, if it ever be met with pure, cannot be said to contain 
organised matter ; but we may readily admit, that any matter capable of solution 
in water absorbed by the root, will pass with it into their vessels ; and such soluble 
matters may be common salt, nitre, potassa, or lime, — also that peculiar compound 
of oxygen and charcoal, which we call carbonic acid ; but assuredly the most minute 
particle of any organised solid substance, even though its bulk do not amount to the 
thousandth part of a grain of dust, can never enter the spongelets of the root. 
To recur to Mr. Henslow : — " Not one," he says, " of all the chemists whom 
the world has yet seen, has been able to combine the elements of inorganic matter, 
so as to form out of them a single organic compound. They can change one organic 
body into another, as starch into sugar ; but they cannot make either starch or sugar 
directly from the elements of which they consist. It is to the vegetable kingdom 
alone that this wonderful faculty belongs, and it is by the leaves of plants that the 
operation is carried on. The crude sap is merely instrumental in supplying the 
leaves with the materials necessary for the formation of organic matter ; it is the 
proper juice created by the leaves, and in which such variety of organic matters 
are dissolved, which forms the real nutritious fluid of the plant, as blood does that 
of the animal. The importance of retaining all tlie leaves (whilst they are still 
living) upon a plant, is sufficiently evident ; not one of them can be abstracted or 
injured without the plant being deprived of a certain amount of ' power ' for 
generating its ' proper juice.'" 
