MINUTE ANATOMY OF THE OMENTUM. 241 



by the surface endothelium. There are no connective-tissue 

 corpuscles within this kind of trabeculse. 



Between a and h we find all intermediary forms, i. e. 

 broader or narrower trabeculae, according to the larger or 

 smaller number of connective-tissue bundles of which they 

 are composed, and between these lie the corresponding 

 connective-tissue corpuscles. Examining more carefully one 

 of the smaller of these intermediary forms of trabeculae, 

 ^. e. one containing a small group of bundles, like the one in 

 fig. vi, we have two important facts. 



First, we see at the points where three or more trabeculae 

 meet, an accumulation of nuclei ; examining these places with 

 a moderate power we find that the nuclei are due chiefly to 

 cells situated between the connective-tissue bundles, the 

 nuclei being surrounded by granular protoplasm. (In prepara- 

 tions prepared with bichromate of potash, and then stained 

 as described above, the nuclei belonging to the covering 

 endothelium cannot be easily distinguished except by very 

 careful focussing ; staining with silver gives satisfactory 

 information.) A second fact of equally great importance is 

 the presence of vacuoles between the bundles of con- 

 nective tissue. In the drawing under consideration we see 

 that these vacuoles are between the bundles, and in a more 

 or less distinct linear arrangement. It is easy to understand 

 how by the increase in size of these vacuoles a group of 

 meshes is established, or how by the coalescence of two or 

 three vacuole meshes of considerable size are formed. 



As in the case of the guinea pig (see above), so also 

 here we find that in some vacuoles are contained nucleated 

 cells. The examination of a number of places like the one 

 represented in fig. vi leads one to suppose that the accu- 

 mulation of nucleated cells at the junction of trabeculae 

 represents the stock from which cells extend by active 

 growth between the bundles, and are destined to become 

 the covering endothelial cells of the latter when this part 

 becomes fenestrated. 



From the preceding description it appears that the meshes or 

 holes in the omentum are caused by the separation of the bun- 

 dles from each other ; that is to say, they appear between the 

 bundles (the connective-tissue corpuscles situated between 

 these representing the endothelial cells after the fenestration 

 of the corresponding parts), and that therefore Ranvier is 

 right against Rollett, according to whom (as mentioned 

 above) each hole is surrounded by a bundle returning in 

 itself. Although the statement of Eollett is not correct in 

 the above form, still it may be rendered correct by slightly 



