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EXTRACTS FROM FOREIGN JOURNALS. 
the chest, let a glass slide be laid against it. On account of its 
natural moisture, the membrane soon adheres to the glass 
while still retaining its normal and physiological condition, pro¬ 
vided no excess of pressure has been put on it. Let the mem 
brane then be carefully divided so that a fragment of it shnl 
be isolated upon the glass, and colored with a few drops of picro 
carminate of ammonia solution, and the following results will be 
observed : 
1st, A fibrous network, formed of connective fasiculi, of vari 
ous sizes and of very fine elastic fibres. The connective fasicul 
are intercrossed in all directions, but in the same plane. They 
thus represent numerous very uneven networks of handsome ap 
pearance. The smallest of these are bound by very delicate 
threads, in the centre of which no capillary vessels can be found 
a condition which explains their great fragility. 
2 d, A layer of endothelial cells, polygonal by reciprocal pres 
sure, upon each of the faces of the serous membrane. The exami 
nation of this endothelium can be made directly in the picro-car 
mine after a few hours, but is better observed in nitrate of silvei 
solution. 
That which is interesting to us is, that in the centre of the 
largest network the two layers of endothelium only are to be 
found; there is no connective tissue between them. It is ai 
these points that the serous surface is most delicate and liable te 
tear. 
When the preparation has succeeded, the membrane present; 
only very few holes, and sometimes none can be seen. But whet 
they do appear, they present special characters. The endothe 
lium appears in them with evidently torn edges, which are formec 
of cells which have assumed the circular form, in the parts where 
they are free; but have a polygonal form when they adhere tc 
surrounding cells. 
In tearing, the endothelial covering retracts. It shrinks 
towards the vascular tracts of the membrane, where it is most 
supported, and as a consequence a certain number of the finest 
trabeculoe are exposed. 
Whether the openings have been artificially formed during the 
