necessarily have been covered by every successive layer of alburnum, without any transmutation of bark into that substance.*

In the second experiment cited by MIRBEL, DUHAMEL has shewn that when a bud of the peach tree, with a piece of bark attached to it, is inserted in a plum stock, a layer of wood perfectly similar to that of the peach tree will be found, in the succeeding winter, beneath the inserted bark. The statement of DUHAMEL is perfectly correct; but the experiment does not by any means prove the conversion of bark into wood; for if it be difficult to conceive (as he remarks) that an inserted piece of bark can deposit a layer of alburnum, it is at least as difficult to conceive how the same piece of bark can be converted into a layer of alburnum of more than twice its own thickness (and the thickness of the alburnum deposited frequently exceeds that of the bark in this proportion), without any perceptible diminution of its own proper substance. The probable operation of the inserted bud, which is a well organized plant, at the period when it becomes capable of being transposed with success, appears also, in this case, to have been overlooked, for I found that when I destroyed the buds in the succeeding winter, and left the bark which belonged to them uninjured, this bark no longer possessed any power to generate alburnum. It nevertheless continued to live, though perfectly inactive, till it became covered by the successive alburnous layers of the stock; and it was found many years afterwards inclosed in the wood. It was, however, still bark, though dry and lifeless, and did not appear to have made any progress towards conversion into wood.

Physique des Arbres, Lib. IV. Ch. III.

In the course of very numerous experiments, which were made to ascertain the manner in which vessels are formed in the reproduced bark, * many circumstances came under my observation which I could adduce in support of my opinion, that bark is never transmuted into alburnum; but I do not think it necessary to trouble you with an account of them; for though much deference is certainly due to the opinions of those naturalists who have adopted the opposite theory, and to the doubts of DUHAMEL, I am not acquainted with a single experiment which warrants the conclusions they have drawn; and I think that were bark really transmuted into alburnum, its progressive changes could only have escaped the eyes of prejudiced, or inattentive observers. In the course of the ensuing spring, I hope to address to you some observations respecting the manner in which the alburnum is generated.

Elton, Dec. 29, 1807.

I am, my dear Sir,

your most obliged obedient servant,

THOMAS AND. KNIGHT.

Phil. Trans. for 1807. .

VII. Some Account of Cretinism. By Henry Reeve, M. D. of Norwich. Communicated by William Hyde Wollaston, M. D. Sec. R. S.

Read February 11, 1808.

FELIX PLATER, in one of his observations, gives the history of a species of mental imbecility, which he saw in passing through the village of Bremis in the Valais. Cretinism, a word of uncertain derivation, is the name employed by the inhabitants of Switzerland to denote this disease, which is endemial in several districts of that country. It had probably existed long in those parts; for PLATER mentions cretins as being very common both in the Valais and in Carinthia, but the peculiar marks of these wretched beings were not generally known before he described them.* Mons. DE SAUSSURE has furnished the most minute and accurate account both of the appearances of the disorder, and of the circumstances which seem to produce it; and Mr. CoxE and several travellers have noticed the symptoms of cretinism, without adducing any satisfactory explanation of the causes to which it may be ascribed. MALACARNI of Turin and Professor ACKERMANN have given a very accurate description of several cretins that they dissected; and besides some detached essays by different authors, a very full account of this malady is to be found in

F. PLATERI Praxeos Medica, Cap. III. Basil. 1656.

an" Essai sur le Goitre et Cretinisme par M. FODERE,” published at Paris in 1800.

My curiosity led me some time ago to inquire more particularly into the nature and causes of cretinism, because it is usually connected with goitre, or bronchocele; I was indeed led to this inquiry, partly by the hope of discovering some function for the thyroid gland, more satisfactory than what is commonly alledged; but in these expectations I have been disappointed.

In the summer of 1805, I had an opportunity of seeing several cretins at Martigny and Sion, and other villages in the Valais; and I was glad to compare what had been written upon that subject, with what my own observation could suggest. By inquiries on the spot, I intended to learn what connection subsisted between weakness of the intellectual faculties and the swelling of the thyroid gland: what were the moral and physical circumstances which could influence the condition of the inhabitants, so as to make idiocy so prevalent; and what were the most efficient modes of relief. The following results I beg leave to lay before the Royal Society.

Cretinism is found not only in the vallies of the Alps, both on the French and Italian side of these mountains, but in the mountainous parts of Germany and Spain; and it was observed in Chinese Tartary by Sir GEORGE STAUNTON, in a part of that country much resembling Switzerland and Savoy in its alpine appearance. The enlargement of the thyroid gland called goitre, is the most striking feature in the unsightly aspect of a cretin; but this is not a constant attendant. His head also is deformed, his stature diminutive, his complexion sickly, his countenance vacant and destitute of meaning, his

lips and eye-lids coarse and prominent, his skin wrinkled and pendulous, his muscles loose and flabby. The qualities of his mind correspond to the deranged state of the body which it inhabits; and cretinism prevails in all the intermediate degrees, from excessive stupidity to complete fatuity.

At a small village, not far distant from Martigny, I examined four cretins. One lad, twelve years old, could speak a few words; he was of a weak and feeble frame, silly, but had no goitre. Another boy, nine years old, was deaf and dumb, idiotic, with no goitre, the only child of his mother, who has a large goitre which affects her respiration and her voice, though in other respects she is intelligent and well formed, and the father enjoys good health; they are not natives of this place. I saw a family in which all the children were cretins; the eldest died a year ago, a miserable object; the second, a girl, twelve years old, is deaf and dumb and crosseyed, and has a monstrous goitre, with just intelligence enough to comprehend a few natural signs; the third, is a boy six years old, small and feeble, abdomen enlarged, no goitre, very feeble in mind and body, not entirely deficient in understanding; the mother had a moderate sized goitre, but was quite free from any mental affection; the father neither goitrous nor stupid, but of a delicate constitution.

There is no necessary connexion between goitre and cretinism, notwithstanding the assertions and ingenious reasoning adduced by FODERE. It is probable, the one has been assumed as the cause of the other, from the enlargement of the thyroid gland being a frequent occurrence in cretins; and as it forcibly strikes the observer from the deformity it occasions, this strong impression may have converted an accidental,