150 GENERAL ANATOMY. 



microscopically examined, it presents manifest villosities: for 

 this reason they have been styled, the simple villous mem- 

 branes. This surface is constantly humected by a liquid. 



186. The serous membranes are generally of a whitish 

 colour, which their transparency renders scarcely sensible r 

 glistening on their free surface, extremely thin yet tolerably 

 strong, more so in fact than the cellular tissue would be if re- 

 duced into lamina of an equal tenuity; they are commonly 

 slightly elastic. 



187. They appear, at first sight nearly homogeneous: al- 

 most always, however, a fibrous appearance, more or less 

 marked, may be observed in various parts of their extent. 

 When torn by distension, they first become loosened, and then 

 reduce themselves into little intermixed, intercrossed, and, as 

 it were, interwoven filaments. Their nature appears very 

 analogous to that of the cellular tissue, from which they only 

 differ by their greater density and the distinct cavity they 

 represent. Between the cellular tissue and the serous mem- 

 branes, there exists a sort of insensible gradation, and the most 

 simple of the serous membranes still partake largely of the 

 nature of the cellular tissue. The very loose cellular tissue 

 in which inflation develops large ampulloe, as that of the pre- 

 puce, that which exists between the great moving muscles 

 and the subcutaneous synovial bursae, constitute a transition 

 between the two tissues. Very numerous white vessels enter 

 into the composition of these membranes. Injections and 

 inflammation penetrate the first with a coloured liquid; the 

 second, the blood, in these vessels render the latter very ap- 

 parent: their number then appears very considerable. We 

 must not, however, confound the vessels peculiar to the serous 

 membrane with those that belong to the subjacent cellular 

 tissue, and which might be supposed to exist in the membrane 

 itself, on account of its transparency. In the peritoneum, for 

 instance, the inflammation must last for a long time to cause 

 the blood to penetrate beyond the sub-serous cellular tissue; 

 and on a slight observation one would be tempted to think it 

 was the peritoneum itself rendered vascular by the disease. It 

 is the same with injections; it is only when they are extreme- 



