bottle of lime-water being placed under it. After filling the other with rain-water, and inverting it in a veffel of the fame, I introduced into it feven and one-fourth ounce-measures of air, that had been confined more than a week with putrid flesh, in a veffel ftanding in water. The Barometer was at the time at 29,81 inches; a Thermometer, placed befide the jars, stood at 56°. The lime-water, in the bottle under the first glafs, became turbid in the space of twenty-four hours. At the end of three days, the barley it contained had fprouted confiderably, while the parcel in the other jar remained unaltered; nor was the bulk of the Azote confined with it increafed or diminished perceptibly. The Barometer and Thermometer standing very nearly at the points fpecified above, when the bell glafs was agitated in water, the inclofed air did not contract in the leaft: a proof that no carbonic acid gas was mixed with it. The jar being taken out of the water, and cleared of the gas, was placed on the table, with a bottle half-full of lime water under it. In fourteen. hours, part of the lime-water was precipitated; and, in feventy-two hours, the grain had sprouted, just as if it had never been expofed to any thing but atmospheric air. I repeated this experiment, at another time, with four drams of steeped barley, and two and a half ounce-meafures of air, being part of the refiduum of a quantity of common air that had been in contact with a folution of liver of fulphur for eight days. The experiment was con

tinued fix days without fhewing the leaft fign of vegetation; but, on admitting common air into the glafs, its contents fprouted freely. This experiment proves decifively, that feeds faturated with moisture have no affinity to Azotic Gas. It alfo appears, that the first stage of vegetation is analogous to combuftion and refpiration, all the three proceffes depending on oxydation by the atmosphere. I fhall clofe this fubject with the following remarks:

I. The only inference in this paper which feems to me doubtful, is, that feeds impregnated with water retain a part of the oxygene they abforb. To determine the matter with more certainty than I have done, the fixth experiment fhould be repeated

over mercury.

II. It is probable, that fome Hydrogene escapes from vegetating feeds, combined with Carbone; because the veffels ufed in the foregoing experiments retained a peculiar fmell, even after being washed in clean water, but the action of the air destroyed it in a few hours.

III. I have found, that steeped grain confined, for four or five days, in fmall quantities of common air, will fometimes vegetate, and not in other cafes. This, perhaps, is owing to variations in the general temperature; for when the Thermometer ftands higher than 56°, it is probable, that the putrefactive fermentation commences fooner than when it is below that point. Laftly, the ufe, and even the neceffity of having the foil very well pulverized,

Sf2

pulverized, for the reception of a crop of grain or pulfe, is explained by the preceding facts and obfervations: For when the turf of a field is reduced to a fine powder, the air finds free accefs to every part of it; and the feeds it contains, being placed in a temperature that is nearly uniform, and supplied with a neceffary portion of humidity from the moift ground, are exposed in the most favourable manner, to the united effects of those causes, which are intended by nature to promote the growth and profperity of the infant plant.

On PLICA POLONICA. By MR. FREDERIC HOFFMAN, Surgeon to the Pruffian Army.-Communicated by DR. FERRIAR.

READ, MARCH 22, 1793.

SYNONYMS. Lues Pocufienfis:* Trica: Trichoma. PoL. Koldun or Gozdz. GERMAN. Juden-zopff: wichtel-zopff: wixel-zorff: weichel-zorff.

DISEASES, the tendency of which is fatal, and

the occurrence frequent, peculiarly claim the attention of the practical phyfician; while morbid affections which appear more rarely, and prefent unusual phænomena, more efpecially attract the enquiries of

Pokufia is a territory of Poland.

thofe

thofe whofe object is the extenfion of general science. The disease termed Plica Polonica is of the latter clafs. It is endemic in Poland; and feldom, if ever, obferved in any other part of Europe. During a long ftay at Breflau in Silefia, I had frequent opportunities of obferving this difeafe: and, as it is at present little known in Britain, I trust a brief narration of the principal circumftances connected with it will not prove uninterefling.

Both fexes are equally liable to the attacks of Plica. It ufually appears during infancy; and but feldom after the age of twenty. When once produced, it continues during the remainder of life. The acceffion of the complaint is in general preceded by irregular fpafmodic affections, pains in different parts of the body, a flow fever, and various diseases of the eyes; all which ceafe immediately on the appearance of the Plica.

The diforder confifts in a præternaturally rapid growth of the hair, with a copious fecretion of a vifcid matter from its bulbs. For the most part, the hairs of the head are alone affected; and that only in peculiar parts. In thefe, the hairs grow confiderably longer than in the reft; and are knotted and entangled with each other; being alfo covered with the vifcid matter which iffues from their roots, and which affifts in gluing them together.

In proportion as the quantity of this gluten, and the implication of the hair increases, it is ftill more and more difficult to clean and comb it; hence

a degree

a degree of Phthiriafis is produced, and the head contracts an extremely foetid fmell, to which however the Polish Peafants are fo much accustomed that they endure it without complaint, or any manifeft inconvenience.

It is alfo an opinion univerfally prevalent with them, that the difeafe is a falutary effort of nature to expel a morbid matter from the body; and that to interrupt the courfe of it would be productive of imuninent danger; hence they make no attempt to cure, or even palliate the complaint. And if we may repofe confidence in Authors of eftablished reputation, morbid affections of a fimilar nature to thofe which precede its occurrence, paralyfis, and even death itself, have fucceeded inprudent attempts' to check the progrefs of the difeafe. In this refpect,' Pica bears fome analogy to the exanthemata, and various chronic cutaneous eruptions.

I am as yet unable to decide whether this complaint is hereditary or not. From fome obfervations indeed it appears, that a predifpofition to it may be tranfmitted from parents to their offspring; but my information on this head is too limited to afcertain the point. In one cafe which fell under my own obfervation, two brothers had Plica, both on the left fide of the head, and in about one third' of their hairs: I learned from them, that their father and grandfather had alfo been affected with the difeafe in a form exactly fimilar.

Befides