TISSUES, ORGANS, AND SYSTEMS. 6S 



regard to the development of these cells, Virchow deduces from 

 Schwann's observations, and Donders from his own investi- 

 gations, the result that the well-known fusiform cells in the 

 rudimentary areolar tissue of embryos are nothing more than 

 the formative cells of the so-called nucleus-fibres ; to which, 

 then, as a consequence, it is added that the proper connective 

 tissue does not proceed from cells, but is nothing else than 

 fibrillated cytoblastema. Hence both these authors agree 

 in placing connective tissue and cartilage side by side and, in 

 comparing the formative cells of the so-called nucleus fibres, 

 which Virchow calls "connective-tissue corpuscles/' (Binde- 

 gewebskbrperchen,) with the cartilage-cells ; the interstitial 

 substance of the cartilage, with the fibrous part of the con- 

 nective tissue. Virchow goes still further, and compares even 

 the bone substance to connective tissue ; especially that which 

 is developed by the ossification of what I have called soft 

 blastema, in which the bone cavities, he supposes, proceed 

 from stellate anastomosing " connective-tissue corpuscles/' 

 a view which seems chiefly to have led him to declare that 

 the nucleus- fibres are hollow, and form a great system of 

 tubules and cavities through the connective tissue, thus 

 probably subserving nutrition. It could be imagined that 

 the nutritious fluid might thus be quickly conducted for 

 considerable distances, and uniformly distributed through the 

 tissue, in which case the nuclei must be considered to be the 

 special regulative portions of the apparatus, while the cells are 

 simply conductors. 



If we submit these different views to the test of observation, 

 it results that much is quite correct, but that some points are 

 untenable. It is true, that the so-called nucleus-fibres are 

 developed from cells ; and the fact is, indeed, noted in certain 

 earlier statements and figures of Valentin, Hassall, Quekett, 

 and others. In the tissues of full-grown animals, it is in 

 many localities unquestionably impossible, in others very 

 difficult, to attain to certainty upon these points, because here, 

 even when the nucleus-fibres still present indications of cells, 

 the cell-membrane so closely embraces the elongated and 

 by no means vanished nucleus, that it is often quite out of the 

 question to decide whether we have a cell with two or more 

 slender processes, or a fusiform or stellate nucleus ; on the other 



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