SECT. 22.] CONNECTIVE TISSUES. 45 



the morphological elements of the lymph and of the blood, which 

 cells are all directly contained in larger and smaller spaces of con- 

 nective substance, certain of which, viz., the capillaries, have, on 

 account of their origin, even been regarded, and, perhaps, correctly, 

 as homologous with the corpuscles of connective tissue (Leydig). 

 Of all these the fat-cells are most intimately allied to connective 

 substance, so that we can scarcely but classify them with the latter, 

 and designate adipose tissue as a form of connective tissue. If we 

 do this, it is but another step to bring into the same rank the 

 tissues of the lymphatic glands, of the splenic pulp, and of the 

 red medulla of bone, in which we find everywhere, along with the 

 cells, bundles of connective tissue ; and there would then result an 

 almost gradual transition to those forms in which the cells appear 

 in large numbers, alone and without any intermixture of con- 

 nective substance, and are only contained in large spaces of the 

 latter, like the nutritive fluid in the blood-vessels. Nevertheless, 

 it appears to me proper, both on histological and physiological 

 grounds, to distinguish between supporting, investing, and expletive 

 connective tissues with their peculiar cells, and the formations 

 contained in spaces within them. Whether or not these, like all 

 the above-mentioned structures, arise with the connective substance 

 from one primitive embryonal basis (the middle germinal layer, 

 Memak), still it is evident, that they, just as well as the muscular and 

 nervous tissues, which likewise originally consist of such cells, are 

 entitled to a distinct place, which is not altered by the circumstance 

 that certain of the cells in question enter into an intimate relation 

 with connective tissue, and, like fat and marrow- cells, even support 

 it in its functions. The above-mentioned spaces of connective 

 substance may (in contradistinction to the intra- cellular cavities 

 of the connective-tissue-corpuscles, lacunae of bone, dental canals, 

 etc.), be most fitly designated as its intercellular spaces, and the 

 matters contained in them as intercellular fluid and intercellular 

 parenchyma. 



Literature. — C. B. Keichert, Verglcichende Beobachtungeu uber das Binde- 

 gewebe und die verrvandten Gebildc. Dorpat. 1854. Virchow, die Idcntit'dt 

 con Knochen-, Knorpel-. und Bindcgavcbslwrperchen, so wieiiber Schleimgerrebe, 

 in "Wurzb. Verhandhmgen, 1851, ii. p. 150 and 314.. Donders, in Ned. Lancet, 



1 85 1, July and August ; and Zcitschrift J. Wiss. Zool. iii. p. 348. Kolliker, 

 ubi r die Entivickclung der sogenannten Kernfascm, der elastischen Fasern und 

 des Bindegewebes, in Wiirz. Verh. iii. p. 1. Henle, in Canst., Jahresb., 185 1, 



1852. v. Hessling, in Lllust. Med. Zeitvng, 1S52, pp.54, 124, 162. C. B. 

 Reichert, Zur Strcitfrage uber die Gebildc der Bindesubstanz, in Mull. Arch., 

 1852, p. 521. Remak, uber die Entstekung des Bindegewebes und des Knot-pels, 



