118 



ON THE ELEMENTARY PARTS OF THE HUMAN FABRIC. 



pearance ; and it is then supposed by Henle to consist of the coalesced nuclei 

 of cells, whose development has been arrested : or, in other words, such 

 Basement-Membrane is formed by the consolidation of a layer of the plastic 

 element, that includes a large number of the granules, which may serve for 

 the development of new cells. Other forms of the Basement-Membrane can 

 be distinctly seen to consist of flattened polygonal cells, closely adherent by 

 their edges ; every one having its own granular nucleus.* It seems to be from 

 these granular germs, sometimes scattered through the membrane, and in other 

 instances collected into certain spots, that the cells of the superjacent Epithe- 

 lium or Epidermis take their origin ; and if this be the case, we must regard 

 the Basement-Membrane as a transitional rather than as a permanent struc- 

 ture, continually disintegrating, and yielding up its contained cell-germs on 

 its free surface, and as constantly being renewed from the blood beneath. 

 For the epidermic structures appear to constitute an exception to the general 

 rule, that the Tissues reproduce themselves ; since they are cast off, without 

 leaving their germs behind them ; and the cells which replace them must be 

 derived from new germs, more directly supplied from the blood than is else- 

 where the case. In the case of the other tissues, whose disintegration takes 

 place inter stitially (so to speak), it would seem probable that, in the very 

 act of the dissolution of the parent-structure, the germs of the new structures 

 destined to replace it are set free ; as happens in the reproduction of the sim- 

 ple Cellular Plants. 



136. It would seem doubtful, also, in regard to the simple Fibrous tissues, 

 whether they are generated by a metamorphosis of Cells, in the same manner 

 as the Osseous, Muscular and Nervous ; or whether they are not produced, 

 like the Basement-Membrane, by the consolidation of a plastic fluid, which 

 has been elaborated by cells. The latter view is the one which the Author 

 has been led to regard as most probable, from the results of his own observa- 

 tions, coupled with those of Messrs. Addison and Gulliver previously adverted 

 to. The Membrane of the Egg-shell, whose structure has been already 

 described ( 118), appears to him to have essentially the same character with 

 the simple Fibrous tissues, which it resembles also in its tenacity (compare 

 Fig. 11 with Fig. 22) ; whilst its origin can scarcely be supposed to be different 

 from that of the fibrous network in the buffy coat of the Blood, or in the 



bands formed by the coagulation of Lymph upon an 

 inflamed surface. The occasional vestiges of cells, 

 which the purely Fibrous tissues display ( 138), 

 and which have been adduced in support of their 

 cellular origin, are not inconsistent with this view. 

 For in the reticulated structures just adverted to, 

 certain bodies are seen, which appear to be nuclei 

 or imperfectly-formed cells (originating probably in 

 germs set free by the rupture of the colourless cor- 

 puscles of the blood), and which closely correspond 

 with the nuclear corpuscles that may be brought 

 into view in the Fibrous tissue. Mr. Addison's 

 observation, too, that the fibres formed in the 

 Liquor Sanguinis, and in plastic exudations, during 

 coagulation, often seem to radiate from the remains 

 of the white corpuscles that have ruptured, or from 

 the little aggregations of granules they contained, 

 gives the explanation of several of the appearances, which have led to the 



with a dilute acid, yields specimens of Basement-Membrane, in a form well adapted for 

 examination. 



* See J. Goodsir, in " Anatomical and Pathological Observations," Chap. I. 



Fig. 21. 



Colourless cells, with ac- 

 tive molecules, and fibres, of 

 fibrine, from Herpes labialis. 



