NOTES AND MEMORANDA. lOl 



plasm. The cells vary in size, and in general the smaller 

 ones are arranged in groups, which correspond to lymphatic 

 lacunae in the basement layer of the peritoneum, while the 

 larger ones correspond to the connective-tissue bundles 

 forming the walls of the lacunse. Stomata were not generally 

 found in the endothelium, the cells being closely apposed to 

 each other. Only in old persons and those who have died 

 from wasting diseases apertures may not uncommonly be 

 found between the cells ; but these the authors consider to be 

 caused by an atrophic process, and not to be a physiological 

 peculiarity. Apertures between the cells are not necessary 

 for the passage of granules or migratory cells, as these may 

 push between the edges of neighbouring cells, thus causing 

 a temporary opening, which closes after their passage. 



Memhrana limitans. — This membrane appears homo- 

 geneous, finely granular, or finely fibrillar, swells up, and 

 becomes invisible in acetic acid, and contains no trace of 

 nuclei. It is perforated by numerous small apertures in those 

 parts which cover subjacent lymphatic lacunae in the base- 

 ment layer. 



The siipjiorfing lai/er nnderWes the membrana limitans, and 

 is formed of wide andfiattenedconnective-tissue bundles, which 

 are collected together into shining cords, separated from each 

 other so as to leave free intervals, and form bridges over the 

 lymphatic lacunae of the basement layer, and immediately 

 under the perforated portions of the membrana limitans, to 

 Avhich they afford a support. 



Basejnent layer. — The reticular stratum consists of rather 

 shining fibrous bundles, whose general direction is from the 

 peripheral parts of the diaphragai to the central tendon. 

 They diverge from each other and again unite, so as to leave 

 intervals (lymphatic lacunae), which communicate freely with 

 each other. From the lacunae bundles pass obliquely upwards 

 to the membrana limitans, where they spread out and form 

 a network of fibres, which becomes fused with those of the 

 supporting layer. The reticular stratum contains large and 

 small blood-vessels, which have a close relationship to the 

 lymphatic lacunae, into the lumen of which they often 

 project more or less distinctly. The compact stratum forms 

 a comparatively continuous layer beneath the reticular layer, 

 and forms the wall of the lacunae which separates them from 

 the subserous layer. It contains blood-vessels and lym- 

 phatics, and consists of horizontal connective-tissue bundles 

 surrounded by numerous elastic fibres. 



The subserous layer, which fixes the peritoneum to the 

 diaphragm, consists of loose connective tissue, and contains 



