1820.] Royal Academy of Sciences. 6^ 



torrent is precipitated down a perpendicular escarpment to the 

 depth of about 50 feet, and where it may be perceived, that, 

 although the basalt on either side is wholly amorphous, or 

 divided only by irregular fissures into imperfect quadrangular 

 masses, yet that, where it lies in immediate contact with the 

 faUino- stream, it exhibits some well worked columns which 

 seem clearly to have been developed by the continued action of 

 the water, and the abrasion of the rock by which the natural 

 structure was obscured. 



EOYAL ACADEMY OF SCIENCES AT PARIS. 



An Analysis of the Labours of the Royal Academy of Sciences 

 of Paris during the Year 1818. 



{Concluded from vol. xv. p. 463.) 



MEDICINE AND SURGERY. 



The membrana pupillaris is that cellular and vascular veil 

 which closes the pupil in the foetus, and is torn, and usually 

 disappears towards the time of the birth. M. Portal has pub- 

 lished some observations on this veil, which he thinks is some- 

 times, hy its not being torn, the occasion of that blindness 

 which occurs in new-bom infants, and which can be easily cured 

 by an operation. M. Portal thinks the new-born infant is void 

 of hearing and smell, as well as of sight, because the nostrils 

 and the cavity of the tympanum are fiUed with mucosity, from 

 which they must be freed before the organs can be of any use. 

 It also sometimes happens that infants are born deaf, and remain 

 so, because the cavity of the tympanum is not emptied. 

 ^ M. Portal, whose work on the enlargement of the heart with- 

 out any dilatation of its cavities was analyzed by us last year, 

 has read in the present a paper on the aneurisms of that organ. 



In this work he has shown that they are very common, and 

 always consist of an enlargement of one or more of the four 

 cavities of the heart, either because their sides have become thin, 

 or have grown thicker; for, in every case, it is the blood which 

 produces either singly, or in concurrence with other causes, this 

 enlargement in one or more of the cavities of the heart, by dis- 

 tending their sides, which are always too weak relatively to its 

 impulse, or because the blood is in too great quantity throughout 

 the whole system of circulation, or because there being some 

 obstacles to its egress from the heart, it is retained there in too 

 great a quantity, by which means it distends its sides : also that 

 the contractions of the sides of the heart, so far from being 

 stronger when these sides are thicker than usual, are, on the 

 contrary, much weaker, if the sides are disorganized by any 

 disease, as they almost always are in that case ; and should it 

 happen that, while the heart is sound, its sides acquire a greater 

 thickaess than usual; they would indeed contract more forcibly. 



