CORNEOUS FILAMENTS OF PERITONEUM OF FROG. 45 



that they are not naked, but surrounded by a membranous 

 covering which blends with the peritoneum. 



If we excise the mesentery of the stomach in the fresh 

 state, and mount it in a small drop of aqueous humour or 

 blood serum, or if we colour it in a ^ per cent, solution of 

 nitrate of silver aiul mount it in glycerine, these structures 

 present a middle portion — a hair-like body — the corneous 

 filament of Remak, and a sacculus. The corneous filament 

 represents a dark spear-shaped body 0"89 to 1'5 mm. long, 

 0021 mm. broad at the middle part and 003 mm. at the 

 base. It comes to a point at the one extremity, and at the other 

 is abruptly truncated. This body is not always broadest 

 at the truncated extremity ; there are not a few that are 

 broadest in the middle. Some of them appear dark yellowish- 

 brown at the truncated extremity. In this case there is also 

 something like a fibrillar structure to be recognised, and it 

 appears, as well, as if fibres penetrated from the covering 

 into this truncated extremity. It has not occurred to me to 

 notice a combination of distinct hollow fibres. The sacculus 

 in whicli these bodies are imbedded is, in most cases, but not 

 in all, raised above the peritoneal surface, to which it is then 

 either connected by one or tAvo thin bridges only ; or, on the 

 other hand, fastened for a greater extent. At times, two 

 sacculi are connected by means of a bridge, being likewise 

 joined to the peritoneum by a tliin bridge only. In every 

 case the sacculus has a complicated structure. On the large 

 and complete formations we observe first the hair-like 

 bodies surrounded by a wider or narrower layer of a substance 

 containing coarse granular structures. This most internal 

 layer of the sacculus is, chiefly at the truncated extremity 

 only, but in some cases also at the portion which corresponds 

 to the pointed extremity of the hair-like body, thickened in a 

 bulb-like fashion. Outside of this follows a membrane, 

 hyaline in profile, and double contoured, which towards the 

 bulbus increases considerably in thickness, and here seems to 

 possess staff-shaped nuclei. External to this membrane there 

 are always, according to the thickness of the sacculus, some- 

 times more, sometimes less numerous, layers of cells, Avhich, 

 when seen in profile, appear spindle-shaped. In each of 

 these a rod-shaped nucleus is to be recognised. The cells 

 are imbedded in a fibrous matrix, and on the bulbus are more 

 strikingly lamellated than on another place. 



In many cases there lie in the bulbus, within those just 

 mentioned, young cells which are compactly pressed together, 

 and consist of a pale protoplasm. In other isolated parts of 

 the sacculus we find smaller isolated groups of young cells 



