OF THE MUCOUS MEMBRANE. 195 



in the different parts of it, and which, the difference of volume 

 excepted, may be compared to the transverse folds or the val- 

 vuli conniventes of the intestines. The villi* perceived by 

 Fallopius and Azelli, described and represented by Helvetius, 

 Lieberkuhn, Hedwig, Rudolph, Meckel, Buerger and several 

 other anatomises, are found, particularly, in the small intestine; 

 they are not so long and are less numerous in the stomach 

 and colon. To have a fair view of them, it is necessary to 

 take a portion of the intestine unchanged by putrefaction, to 

 open it carefully, to moisten it with drops of water until the sur- 

 face is completely covered by it, and then to examine it through 

 a lens, which will increase its diameter about forty times. 



268. To make this examination as well as others analogous 

 to it, I have used, with much advantage, a little apparatus 

 composed of a glass sphere of small diameter, open on one 

 fourth of its surface, and of an operculum a little smaller than 

 the opening, and of a thin layer of wax. The part, to be exa- 

 mined is to be fixed on the wax with small pins, it is then 

 plunged into water with the open sphere, which is to be filled 

 with that liquid, and afterward, placed on the operculum. The 

 apparatus is now withdrawn, and the object to be examined 

 is thus covered by a little lenticular mass of water, which aug- 

 ments its diameter. 



269. Examined in either of these two ways, the villi ap- 

 pears neither conical, cylindrical, canaliform, nor enlarged at 

 the summit, as many authors have described them, but rather 

 in the form of little leaves or laminulse, whose numbers are so 

 great as to convey the appearance of a luxuriant grass-plot. 

 These little leaves, variously bent and consequently seen in 

 various aspects, appear to have different forms: neither are 

 they everywhere the same: those of the pyloric half of the 



* See among other authors, Helvetius. Mem. de fAcademie des Sciences. 

 Paris, 1721. T. N. Lieberkuhn. de Fair, et ad. Fillos. Intest. horn. Lug-d. 

 Bat. 1744, 4to. R. A. Hedwig. Disquis. Ampull. Lieberkuhnii. physico- 

 micros. Lips. 1794, 4to. C. A. Rudolphi. in Reils Archiv. der physioL IV. 

 et Anal, physiol. abhandl. Berol. 1802. J. F. Meckel in Deutches Archiv. 

 fur die physioL III. H. Buerger. Examen. micros. Villos. intestin. cum 

 iconibus. Halae, 1819 8vo. 



