MINUTE ANATOMY OF THE OMENTUM. 237 



of, that indistinctly granular substance, for in some we may 

 distinguish under a high power very delicate fibrils, while 

 in still others the whole mass seems to be composed of a more 

 or less distinctly fibrillar tissue. In the latter case the fibrils 

 have either a concentric arrangement, as in fig. v, or they form 

 a thinner or thicker bundle, much convoluted, and situated 

 ])arallel to the surface of the corresponding trabeculse (as in 

 fig. iv), or vertical to it. The fibrillar nature of such a 

 bundle is very well shown if in the course of preparing the 

 specimen the endothelial covering breaks and the bundle of 

 the bud-like structure becomes uncoiled. It may then be 

 ascertained that there exists no difference between this 

 bundle and the ordinary connective-tissue bundles of the 

 trabeculse. As the contents of the bud-like structures 

 become more distinctly fibrillar we find that it enters also 

 into a closer connection with the subjacent connective tissue. 

 The question presents itself now, How do these bud-like 

 structures develop ? The earliest, or what appears to be the 

 earliest, stage is a small prominence due to the presence of 

 one, two, or three, or probably more, slightly flattened cells, 

 the substance and nucleus of which places them in the same 

 category with the endothelial cells of the surface. In the 

 next stage the substance of these cells, except the one 

 covering the prominence, becomes indistinctly granular, the 

 outlines of the cells becoming at the same time indistinct or 

 altogether lost ; whereas the nuclei lose their power of 

 staining with haematoxylin or carmine ; their outline becomes 

 soon indistinct, and finally they are altogether lost. In figs. 

 i, iii, and v very faint outlines of nuclei are still dis- 

 tinguishable. 



The description hitherto given applies to the examination 

 of the omentum of rat, but also in that of half-grown 

 dog have I observed similar bud-like structures, only these 

 are less numerous. I should say that those that I have seen, 

 were of the same kind as that represented in fig.v; theyshowed 

 already fibrillar structures, the fibrils being arranged concen- 

 trically, and among them were remnants of one or two 

 nuclei. 



So that it appears that bundles of fibrillar connective 

 tissue are being formed in the omentum by the direct con- 

 version of cells. These cells are in all respects similar to 

 endothelial cells. This is in conformity with an almost 

 generally assumed theory ; it is, however, not quite in accord- 

 ance with what RoUett states (' Strieker's Handbook,' 

 chapter on Connective Tissue) as regards the development of 

 the connective-tissue bundles of the foetal omentum. In my 



