It is taken for granted that the seeds of the farm are perfectly indifferent. Provided plenty of manure is put into soil, the intimate laws and habits of the seeds and plants to be grown may be ignored; the result will be proportional solely to the manure. Pap of all sorts has been manufactured regardless of cost; feeding-bottles of the most attractive design have been presented; but whether the child, Flora's little pale sprawling embryo, should have its head or its heels uppermost, has been mostly regarded as immaterial.

Now, the production of certain plants is the chief object of agriculture. A full discussion, therefore, of the biology of these plants is primarily demanded before chemistry can be intelligently enlisted. It is not here denied that much is already known, both formally and instinctively; but it can hardly be denied that Agricultural Botany has been somewhat left behind. The above experiments show that chemistry cannot announce the full verdict of nature; the botanical members of the jury must no longer be disregarded. In fact, the true position of Agricultural Chemistry is that of handmaid to Agricultural Botany. In this relationship the two have yet a wide field for harmonious. conquest.

There is an unscientific spirit abroad teaching that no experiments are of any value unless they can bring an augmentation to the supply of food. But true experiments are for finding the constitution of nature, that life may train itself into harmony therewith; and an experiment which proves that in any direction, under existing knowledge, a limit has been reached, is as valuable a lesson as an experiment which announces another ton upon the

acre.

The time has probably come when we must be content with small advances and diminishing profits. We have all heard of the botanical benefactor who makes two blades of grass to grow where one grew before: but the value of such a benefaction depends on its cost. If the new blade costs a halfpenny and sells for a farthing, it will be left to wither. It is only upon rare occasions that a second blade can be introduced by pure intellect, free of all charge. It is one province of Agricultural Botany to find out those biological

conditions in which a plant is able most fully to appropriate the gratis stores of nature. If a large turnip seed grows a larger turnip, entirely by draughts upon the manures supplied, it is a calculation whether its use is an improvement or not; but if a part of the larger bulk is derived from atmospheric elements, we have an advantage of that order which costs nothing.

In view of the considerations thus suggested, I make. bold to think that the chief Botanical Society in Scotland ought to take measures for giving a more prominent position to Agricultural Botany than it has hitherto occupied.

APPENDIX.

Average of Heaviest 10 of Heaviest 10 of Dif. of Aver.
Small Seeds. Large Seeds. Small Seeds. Weight.

V. Remarks on Professor E. Morren's Views of Vegetable Digestion. By I. BAYLEY BALFOUR, Sc.D., M.B., F.L.S.

(Read 8th March 1877.)

Professor Morren, of Liege, has recently published a paper on the subject of vegetable digestion as a supplement to his well-known observations on carnivorous plants.

The object of the paper is to show that digestion is not a function peculiar to the so-called carnivorous plants, but is a universal process in all living beings, vegetable as well* as animal, and that the facts narrated of the carnivorous plants, though doubted by many, are yet quite in accordance with the general theory of plant nutrition. Digestion, he seeks to show, is necessary for and precedes assimilation.

Animal digestion is essentially a process of fermentation,

-an hydration followed by decomposition,-resulting in the conversion of complex colloidal substances into more diffusible, and therefore absorbable compounds. This process of digestion takes place in the alimentary tract, the ferments by which it is effected being contained in the juices which are poured into the various parts of the tract. As yet our knowledge of these ferments is far from complete, but they seem to be pretty numerous, and may be arranged in three classes:

1. Amylolytic, or Sugar-forming-transform starch, glycogen, &c., into sugar, with absorption of water. These are present in the saliva and pancreatic juice, in the liver, and in other organs.

2. Fat-decomposing, which cause fats to combine with the elements of water, and to decompose into fatty acids and glycerine, the process being one of emulsionisation and saponification. A ferment of this kind occurs in the pancreatic juice.

3. Those decomposing albuminous bodies. They convert soluble and coagulated albuminous bodies into peptones and then into leucine, tyrosine, &c., and are found in the gastric, pancreatic, and intestinal juices.

By the action of the various animal juices, through the influence of the contained ferments, the food taken into the alimentary tract is digested, is so acted upon as to be brought into a state in which it can be absorbed by the lacteals, and becomes assimilated within the tissues of the organism.

But what is observed in the animal is true of the vegetable economy also. All plauts digest, and their digestion, in all essential particulars, is the same as that of animals. It is a process in them preliminary to and necessary for assimilation, and substances of a like nature are affected, and by means of similar ferments. Digestion is a general .and essential function in the nutrition of plants.

The ferments by which the process is effected form part of the vegetable organism, and they are, perhaps, even more numerous than in animals, and they may be arranged in the same classes.

Of amylolytic ferments we find diastase corresponding to the ptyalin of the saliva and to one of the ferments

in the pancreatic juice. By it starch is first of all decomposed into dextrine and glucose, and finally altogether into glucose. This has been found in barley and other cereals in the process of germination, its generation being the object of malting. It is also found. in the potato, especially near the eyes. Saccharose is a substance abundantly found in many tissues of plants before flowering, specially in the sugar cane and the beetroot. In this form it is not absorbable, and that it may be so it has to be digested. This is effected by a ferment which splits, or, as it is termed, inverts it, the result being glucose, and an uncrystallisable form of sugar, levulose. The ferment inversif corresponds with one found in the intestinal juice, which, according to Paschutin, converts cane into grape sugar. The saccharose having been digested, the resulting products are absorbed and converted into cellulose by the aid of other ferments; but a certain amount of the glucose is consumed in respiration.

Emulsive ferments, or those of the second class, certainly exist in plants. Oleaginous grains, if bruised in water, give an emulsion soon followed by the production of glycerine and fatty acid. This is what takes place during germination, but the precise method of final transference of the materials, and their application to the requirements of assimilation and respiration is unknown as yet. That oils and fats do constitute stores of nutriment. for plants there can be little doubt, and such are specially seen in the grains of Cruciferæ, Papaveraceæ, Linaceœ; in the bulbs of Liliaceæ, &c.

Ferments of the class decomposing albuminous bodies also occur in plants. Albuminoids are stored mainly in the seeds of plants in the form of glutin, aleurone, &c., and albumen in the form of legumin is also found. These occur in the albumen (peri and endosperm) and in the cotyledons. As the young plant grows they are changed and assimilated. The exact nature of the ferment which effects this has been determined in the case of Vicia sativa, in the seeds of which, when germinating, the legumin is gradually changed into leucin and asparagin. The ferment was found on separation to transform fibrin into peptone; it is therefore of a nature similar to the pepsin of the gastric juice. Pepsin itself, or a

substance nearly identical with it, has been found in the juice on the glands of the Drosera, and it also occurs, according to Dr Masters, in the nectar of the flowers of Hellebore. The latex of Carica Papaya has also long been known as having a digestive power.

It is certain, then, that a pepsin ferment exists in some plants, and no doubt if investigations were carried out it would be found in many others. It is also evident that in plants there is a digestion of starch, sugar, fat, and of albu-. minous materials, by which they are rendered absorbable. and assimilable, and this is precisely the normal digestive process in animals.

But in addition to these there are in certain plants other digestive processes, if they may be so called, which are not represented in the animal economy. As instances, Professor Morren cites the formation of essential oil of bitter almonds, along with hydrocyanic acid, glucose, and formic acid, from the amygdalin contained in the seeds of the bitter almond by the action of the albuminous ferment synaptase or emulsin which also exists in the seeds. Similarly many other glucosides are decomposed through the influence of synaptase, e.g., salicin in the bark of the willow yields saligenin and glucose. Again, a ferment erythrozyme is said to convert the colouring matter of madder into glucose and another colouring substance. Then the essence of mustard (sulpho-carbimide of allyle) results from the action of a ferment myrosin, causing the decomposition of the myronic acid and potash salt in the seeds of black mustard (Sinapis nigra). Lastly, there is the pectic fermentation by which the pectose of ripe fruits under the influence of the ferment pectase is converted into pectic and pectosic acids.

Many other examples might be pointed out, but these are sufficient to show that digestive fermentation is more varied in plants than in animals; the general effect being the transformation of stored plasmic matters into soluble crystalloids which are diffusible and assimilable.

Vegetable digestion takes place chiefly in the reservoirs of nutriment,—seeds, tubers, roots, bark, pith,—and most in spring, when tissues are impregnated with water, excited by heat, and animated by respiration. It would, indeed,