the hottest part of his flues; but, I think, not without some ill consequences. His machinery is a good deal superior to mine, and his skill and science in no degree inferior; but his melons, though very large, and apparently perfect, are generally much surpassed by mine in richness and flavour. When sulphur is made to evaporate, some uncombined acid flies off, and this Mr. Williams suspects (and I agree with him in opinion) to operate injuriously upon the health of his plants. It seems probable that the same uncombined acid would cause the flowers of sulphur to operate injuriously; but, though I have often applied it in large quantities, I never witnessed any ill effects."

22. Meteorological Journal, &c., for the Year 1836. By Mr. Thompson.

23. An Account of some further Experiments made in the Garden of the Society, in the Year 1836, relative to the Cultivation of Potatoes. By Mr. Robert Thompson. Read December 6. 1836.

This paper, as containing not only original experiments made in 1836, but a summary of all those made in 1831 and 1832, is by far the most valuable that has appeared on the subject of the Potato in these Transactions.

"In the year 1831, experiments were made with the view of ascertaining the effect of planting the sets of potatoes much wider apart than usual, in order to give the foliage a greater exposure to light. Whole tubers were accordingly planted in spaces containing 16 sq. ft. The result was, that stronggrowing sorts, including a number of Mr. Knight's seedlings, produced fully an average, whilst a few gave a very great crop. But although one of the latter produced at the rate of 21 t. 13 cwt. 59 lb., a weak-growing sort produced only 1 t. 5 cwt. 92 lb. The vigorous could avail themselves of their ample space, which they occupied with their stems and foliage to the full extent; the weaker could not. Hence the propriety of suiting the distance of planting to the vigour of the sort. [See p. 396.]

"In the year 1832, experiments were made with regard to the relative produce of sets from whole tubers, and from single eyes. The result was in favour of the latter by upwards of 7 cwt. per acre, and considerably more on comparison of the clear produce after deducting the weight of sets employed in both cases. [See p. 347.]

"The trials of 1831 gave rise to further experiments with regard to the space between the sets. Accordingly, in 1834, another experiment was made, for the purpose of ascertaining the most preferable distance at which the sets of commonly cultivated varieties should be planted; and at the same time a repetition was made of the comparison between whole tubers and single eyes. The distances between the rows were 2 ft., 2 ft., 1 ft., and 6 in. The result with regard to distance was, that the crop was found to be greatest where the distance between the rows was most in accordance with the height of the stems; and the most uniformly abundant produce was from rows 2 ft. apart. The comparison between whole tubers and single eyes was still found to be in favour of the latter.

"The experiments in the present season [1836] have been made with regard to

"First, the time of planting; first week in March, and first week in April. Second, the sets; whole tubers, bases, and points of tubers.

66

Third, the depth; 3 in., 4 in., 6 in., and 9 in.

"A piece of ground in the kitchen-garden, which was previously in grass, was trenched and planted with the bread-fruit potato, a sort which for productiveness is, perhaps, unequalled near London by any other of so fine a quality. The ground was divided very exactly into six equal parts. Three of these were planted respectively with whole tubers, bases, and points of tubers, in the first week in March; the other three compartments in a similar manner, in the first week in April. The following table exhibits the results, calculated for an acre:

"It appears from the above, that the March plantation exceeds that of April by i ton 5 cwt. 42 lb.; and farther, that the average produce of the points of tubers exceeds that of whole tubers by I ton 16 cwt. 87 lb., and of the base of tubers by 1 ton 15 cwt. 944 lb. Consequently, the lowest produce is from the whole sets; a little above the latter is that from the base; and the points of the tubers rank considerably above either. This superiority appears to take place in the March planting; for of those planted in April the whole tubers had the advantage with regard to produce.

"Sir George S. Mackenzie obtained a different result from different parts of the tuber. Cuts from the base gave a return of 26 lb., middle 20 lb., and points 24 lb.; but, from the following communication, it appears that he was not fully satisfied in regard to the experiment having been fairly made.

"The experiment, the result of which I communicated last year, comparing the respective produce of the cuts taken from the root end, the middle, and the rose end of a potato, was made, as I mentioned, by the gardener then in my service. Last spring I directed the experiment to be repeated; but my gardener misunderstanding me planted root-cuts, &c., from different potatoes of one sort, instead of all the cuts to be compared being from one tuber. result is as follows:

The

'Root-end cuts, 26 lb. Middle, 20 lb. Rose, or crown end, 24 lb. There were 20 cuts of each sort planted at the usual distance, and a single eye in each cut. Though this does not give a strict comparison of cuts from one tuber, yet it may be regarded as giving a fair mean result. The inferiority of the middle cuts is remarkable; and it appears of some importance to repeat the experiment with different varieties of the potato, attending careWhen the eyes are crowded, as fully that only one eye shall be in each cut. I am aware in the crown, or rose, end, they should be all cut away but one. that it has been the universal opinion that the crown end is the most productive; but this appears to have been taken for granted, and not deduced from experiment. The great number of eyes, also, at the crown end, may have contributed to an increased produce. In planting a field it is always advantageous to have at least two eyes, lest one should be cut off by frost.' "In order to try the effects of different depths of planting, a quarter was divided into four equal parts, and planted with sets in the second week in April, at the respective depths of 3, 4, 6, and 9 inches. The results computed At 3 in., 13t. 14 lb.; 4 in., 14t. 1 cwt. 18 lb. ; for an acre are as follows:

6 in., 14 t. 11 cwt. 4 lb. ; 9 in., 13 t. 111 lb.

"The greatest produce was from the plantation at 6 in. deep; and next to it, from that at 4 in. Those planted only 3 in. deep gave the least return.

Many of the sets buried 9 in. did not vegetate, or at least failed in reaching the surface. This was also found to be the case by Hasler Hollist, Esq., in 1835, when he adopted the mode of deep planting. The results of his experiments are detailed in the following note:

"I have this year renewed my experiments on the potatoes you sent me in 1833 from Mr. Knight's collection.

“I planted in the latter end of March, and at intervals during the whole month of April, but I am satisfied I was, contrary to the received opinion, too early in some instances, particularly with Mr. Knight's No. 2.

"I also planted at various depths, 9 in., 7 in., and from 5 in. to 6 in. In nearly every instance the shallow planting has succeeded, but in none the deepest, and in the latter case many of the sets have not vegetated at all, many more have not reached the surface.

"A few single eyes of the Downton Yam, literally parings, have yielded very nearly as much as the full-sized sets. I think I could say quite as much if the tubers from which they were cut were added to their actual produce.

"Some of these statements appear so singular that I feel a hesitation in mentioning; them but, whether from the unfavourable season, mismanagement, or what other cause I know not, certain it is, that these are my results. "P.S. The soil is a loamy sand, and friable.'"

MISCELLANEOUS INTELLIGENCE.

ART. I. General Notices.

INFLUENCE of various Circumstances in the Growth of Plants in modifying their Physiological Action. Extracted from a paper by Dr. Christison, read before the Royal Society of Edinburgh, Feb. 3. 1840. "The author commenced

with some remarks on the various causes by which the action of plants and of their products on the animal body may be modified, and on the great vagueness and uncertainty of the information at present possessed in regard to the influence of those causes which seem to arise in peculiar circumstances of vegetation, more especially climate, weather, soil, and the progress of vegetation. He then stated the sources of information on these points; namely, the curative or therapeutic action of drugs on man, their effects on the healthy function, both of man and animals, either as medicines or as poisons, their sensible qualities, and their chemical analysis; and he assigned reasons for discarding the first of these from the enquiry, and for trusting, in a great measure, to the criterions derived from sensible qualities, from the effects of poisons on the lower animals, and from chemical analysis.

"The remaining part of the present paper was confined chiefly to the influence of the progress of vegetation on the activity of plants. Doubts were thrown, by the results of his investigations, on most of the current doctrines on this head; but the present state of the enquiry did not lead to any general inferences being drawn with confidence.

"An extended statement was made upon the influence of the progress of vegetation upon many of the active species of the natural family Ranunculaceæ. It was stated, that in the acrid species of the genera Ranunculus, Anemone, and Clematis, the acridity, which is the same throughout them all in quality, is possessed in nearly equal activity by the leaves, from an early period in the spring until they are about to decay; but that it exists in the germens only while they are green, and disappears there entirely as the seeds ripen. In the acrid species of Aconitum, the acridity of the leaves, on the contrary, continues only until the seeds begin to form, and then gradually, but quickly, disappears as they ripen, while the seeds acquire precisely the same peculiar kind of acridity. The narcotic properties of the leaves, however, do

not undergo the same singular change, but continue undiminished after the seeds are mostly ripe, and probably, indeed, as long as the leaves themselves retain their freshness. The acridity of the genus Helleborus is probably governed by circumstances different from any of those already mentioned; but the experiments already made are insufficient to point out the true rule. In the course of these observations many remarks were also made on the nature of the acridity possessed by the different species, upon which incorrect ideas at present very generally prevail; several material corrections were also suggested as to the general opinions respecting the influence of heat, desiccation, and time upon their acridity; and a short allusion was made to the properties of a remarkably crystalline principle which the author discovered in one of the species of Ranunculus, and which appeared to him to be the ingredient upon which the activity of that genus depends.

"The author next entered into some details regarding the influence of the progress of vegetation on narcotic plants, and commenced with the natural family Amygdaleæ, the leaves of several of which are eminently poisonous, in consequence of containing, or producing when bruised, a hydrocyanated essential oil. He showed that this oil abounds most in the leaves of the cherry laurel (Cerasus Lauro-cerasus), when they are young and undeveloped; and that it goes on diminishing gradually in proportion to their weight, as they increase in age and vigour, until the commencement of their second season, when the old leaves, though plump and luxuriant, do not contain above an eighth or tenth of what they contained in the infant state, or of what is contained in the young undeveloped leaves of the same period. This is a complete reversal of the generally admitted law in respect of the formation of volatile oils in leaves.

"The consideration of this fact led to some statements upon the mode and form in which some essential oils and other active principles exist in the leaves of plants; and the conclusion was drawn, that in all probability many active principles, which are separated from plants by simple processes, do not exist ready-formed in the leaves; but, as in the familiar case of the mustard seed and bitter almond, are only developed when the structure of the leaves is broken up, and principles of a different kind, secreted in distinct cells, are brought in contact with one another or with water.

"The remaining departments of the investigation were postponed; but further observations were promised upon the influence of the progress of vegetation on the solanaceous and umbelliferous plants, and likewise on the effects of soil and climate."

From the above extract it may be gathered why cattle reject the Ranúnculus àcris, or common buttercup of the meadow, while green, but do not object to it, but are even said to be fond of it, in a state of hay. - Cond.

Temperature of Plants. M. Dutrochet, some years ago, proved by experiment that living plants have a proper heat; and other experiments have recently been made by M. Van Beck, and read to the French Academy in January last, confirming the fact. The maximum of inherent heat which M. Van Beck found, on September 29th, an hour and a quarter after noon, in a young leaf of Sedum Cotyledon, was about 0·25° centigrade, or about something more than half a degree of Fahrenheit. In rainy and dull days the heat was not so great as when the weather was calm and clear. The following observations are interesting, as tending to show the probable advantages of a free circulation of the air among plants; though, as the writer observes, the subject requires to be farther examined.

"A singular phenomenon, which I have always observed in the course of my experiments, is, that, on suddenly raising the bell-glass which cut off all communication between the air of the apartment and that of the plant, the heat of the latter always rose suddenly some tenths of a degree. This phenomenon, however, lasted only a few minutes; the magnetic needle soon retrograded, passing zero of the scale, and showing, by its opposite and permanent deviation, that the living plant had a much lower temperature than the dead leaf, as is always the case in the atmosphere.

"Is this phenomenon to be ascribed to the instantaneous access of the free air to the plant, which, by stimulating its vital functions, which were depressed by its having been kept in a less pure air, augments at the same time its proper heat, before the counteracting and frigorific influence of reestablished evaporation has had time to make itself felt?

"This I cannot venture to decide; but I hope that other philosophers and naturalists will engage in these researches, which, if I am not deceived, may yet throw light on many an interesting question in vegetable physiology." (Compte Rendu, &c., as quoted in Jam. Jour. for April, 1840, p. 333.)

The Effect of Light passing through coloured Glass on Plants (p. 301.) is a subject worth deep attention, and opens a wide field for observation. Some time ago I had two pine stoves darkened with hot lime and water, with a little size to make it stick on. I did this to save the trouble of constantly shading, and I find it not only to break the rays of the sun, but that in very bright days it was scarcely necesssary to give air. The question is, whether a dark colour would not be better than this whitewash? It is well known that pines can be grown faster in summer in pits glazed with dark green glass than in houses covered with clear glass; and I have no doubt but that a coloured mixture to darken the glass through the middle of summer would prove highly beneficial to the pine. However, I will try the experiment on one house.— John Spencer. Bowood Gardens, June 4. 1840.

A new Cedar. If the accompanying extracts and remarks should arrest the attention of any traveller who can procure seeds, or rather cones, from the trees mentioned, he may discover a new cedar; at any rate, he will earn the commendation of scientific men, if, by forwarding such seeds to England, he will enable us to ascertain precisely the trees referred to.

"From Debaree are seen the trees which surround the church of Tchambelga, which Bruce took for cedars, and Salt (at Taranta) for firs; but they resemble neither the cedars of Lebanon nor the firs of Europe; it is rather a mixture of both, with thorns (?) even more tender than those of the cedar but its fruit resembles altogether the fruit of the juniper tree it is almost the only wood for building that there is in Abyssinia." (Gobat's Abyssinia.)

;

The place to which I imagine Gobat refers is, in Salt's Voyage to Abyssinia, 4to, p. 236.," a bed of chalk-stone; and wherever this prevailed an extensive grove of a hardy kind of cedar, called Tûd, flourished in abundance."

I have also lately met (but cannot remember where, [in the Transactions of the Geographical Society of London]) with the assertion, that on the " Cedar Mountains," Cape of Good Hope, are abundance of the cedars of Lebanon. And, in an account of the Madeiras (from whence it would not be difficult to procure cones), it is said that the forests formerly covering the islands have disappeared; save that in the remote parts of the mountains we may still occasionally meet with " a species of cedar." Were I to indulge in conjecture, I should guess the tree mentioned by Salt and Gobat may be nearly allied to, or identical with, the cypress of Goa (Cupressus lusitánica). I would add that Abyssinia, approached now so speedily and easily, and where Europeans, and particularly Englishmen, have little to fear, presents a most tempting field to the practical botanist; offering, as it does, a vegetation of the utmost variety, from the tropical productions of the valleys to the lichens of its snow-clad mountains.-W. H. W. Derby, Feb. 20. 1840.

Beaumontia grandiflora.—If the reader will turn to p. 236. of this volume he will see a speculative notion of mine for flowering the Beaumóntia grandiflora. This old-fashioned plant is very unwilling to flower with us in the stoves, and, if treated as a green-house climber, it soon gets stunted and never flowers at all. This was a great favourite plant with my much lamented late employer, W. Gordon, Esq., of Haffield, and we tried many experiments with it there for nine or ten years to get it into flower, and only succeeded once. It was among the first plants that I tried at Kingsbury, in the way of experiment. I planted it out into a border in the orchidaceous house which runs at the back of the conservatory, and for the first season I trained it in the same house. In the spring of 1839, I introduced the head of it through the back