TISSUES, ORGANS, AND .SYSTEMS. 09 



seems to me to be comprehensible, only when we recollect that 

 these authors arrived at it more upon theoretical grounds, 

 than by direct observation. With Virchow, a passage in 

 Schwann appears to have been conclusive, where he describes 

 the embryouic connective tissue as a gelatinous homogeneous 

 mass, which dissolves upon boiling, and contains cells dis- 

 tributed through it which are not affected by the boiling. 

 Virchow does not hesitate to extend this to all connective 

 tissue, and to assume that the substance soluble in water 

 answers to the subsequently fibrous connective tissue, while the 

 insoluble cells are the formative cells of the so-called nucleus- 

 fibres. Here, however, he has omitted to notice, that Schwann 

 speaks only of a determinate form of tissue, the lax or areolated, 

 and describes in a totally different manner the formation of the 

 more solid connective tissue, e. g. of a tendon. In this case 

 we find, in direct contrast to the former, no trace of cyto- 

 blastema, which can in no way be directly observed, the 

 tendon consisting throughout of fibre-cells, either isolated or 

 united into bundles of connective tissue. 



To observe this, however, the examination must be made at 

 a very early period, since, as Schwann has justly remarked, 

 the elements of the fibrous tissue are very early developed ; a 

 circumstance from neglecting to observe which, it seems that 

 Donders has been led to adopt the same view as Virchow. For 

 my own part I have found Schwann's statements confirmed in all 

 essential points, with the single exception that he was unac- 

 quainted with the formative cells of the elastic fibres, and con- 

 founds them with those of the connective tissue. My obser- 

 vations upon these points are to be found in the following 

 section. Hence I cannot admit that cartilage and connective 

 tissue are nearly allied, inasmuch as the fundamental sub- 

 stances of both, even if chemically agreeing, yet, genetically, 

 are very different. 



Literature. — A. Eulenberg, f detela elastica/ 1836; Virchow, 

 1 die Identitat von Knochen, Knorpel und Bindegewebskbr- 

 perchen, sowie ueber Schleimgewebe/ in the 'Verhandlungen 

 der Phys. Med. Gesellschaft in YViirzburg/ Bd. II, 1851, 

 p. 150 ; and ' Weitere Beitrage z. Kenntniss d. Structur der 

 Gewebe der Bindesubstauz.' Ebend. II, p. 314; Donders in 

 the Nederlansch Lancet./ 1851, July and August; and in the 



