1305. The fact that earthy and saline matters were different in different plants was known to the earlier vegetable physiologists, though they do not appear to have drawn any practical deductions from the facts they ascertained. Jacquin states, that the ashes of glass-wort (Salsola Soda), when it grows in inland situations, afford the vegetable alkali; but when it grows on the sea-shore, where compounds which afford the fossil alkali are more abundant, the ashes yield that substance. Du Hamel found that plants which usually grow on the sea-shore made small progress when planted in soils containing little common salt. The sun-flower, when growing in lands containing no nitre, does not afford that substance; though, when watered by a solution of nitre, it yields nitre abundantly. The tables of De Saussure show that the ashes of plants are similar in constitution to the soils in which they have vegetated. De Saussure made plants grow in solutions of different salts; and he ascertained that, in all cases, certain portions of the salts were absorbed by the plants, and found unaltered in their organs. Even animals do not appear to possess the power of forming the alkaline and earthy substances. Dr. Fordyce found that when canary birds, at the time they were laying eggs, were deprived of access to carbonate of lime, their eggs had soft shells; and the same result, from a similar cause, has been observed in the eggs of common domestic fowls.
