588 



AMERICAN MUSEUM OF NATURAL HISTORY 



Skeleton — Cont'd. 



The most comprehensive general treatise 

 on the origin and development of connective 

 tissue {in German) , with an extensive 

 bibliography, is *Merkel, F. 1909.1. 



Various papers on the development, his- 

 tology, histogenesis, etc., of connective 

 tissue are Ebner, V. 1896.1; Ferguson, 

 J. S. 1912.1; Goldschmidt, R. 1908.1; 

 •Key, A. & Retzius, G. 1875.1; Mtiller, 

 E. 1912.1; Polieard, A. 1902.1; Stud- 

 nieka, F. K. 1897.6, 1902.1, 1906.2, 1907.1; 

 •Szily, A. 1908.1. 



The umbilical cord of mammals is 

 composed of a mesenchymal tissue known as 

 " mucous tissue." For the structure of an 

 analogous connective tissue in the " um- 

 bilical cord " {yolk-sac) of Torpedo, see 

 Laguesse, G. E. 1911.1, 1913.1. 



For the references to "Fat, or adipose 

 tissue," which is formed from areolar con- 

 nective tissue, see under Chemistry. 

 Cartilage 



Cartilage, a dense tissue possessing flexi- 

 bility and elasticity, forms the skeletal tissue 

 of Cyclostomes and Elasmobranchs and is in 

 these forms never replaced by bone. 



In the embryo or larval bony fish (Teleost), 

 and in all higher vertebrates, the skeleton is 

 originally formed of hyaUne cartilage, which is 

 later replaced by bone. 



In adult Selachians, cartilaginous structures, 

 such as the vertebrse, usually become " calcified" 

 or hardened by the deposition of calcium carbo- 

 nate in the form of polygonal plates between the 

 peripheral cartilage cells, as is best shown by 

 Lubosch (W. 1909.1) and by Roth (W. 1911.1, 

 p. 496). Despite the statements of Stark (James 

 1844.2), true bone is not developed in these 

 fishes. 



The origin of cartilage is diflScult to follow. 

 As quoted from an abstract in the Journ. Roy. 

 Micro. Soc, 1898, 2nd. series, vol. 17, p. 290, 

 '* Prof. F. K. Studnieka, [1898.4] shows that the 

 origin of cartilage does not imply occurrence of 

 special cells. In the post-embryonic life of 

 Cyclostomes, cartilage may arise from (1) the 

 dense connective-tissue of perichondrium and 

 fascia; (2) the loose connective-tissue; (3) the 

 Bo-called Schleimknorpel; (4) the Vorknorpel 

 (vesicular supporting tissue of Schaffer) ; (5) 

 the axial connective-tissue of the caudal fin; 

 (6) highly specialized tissue, such as fatty tissue; 

 and (7) the epithelium of the notochord." 



The most extensive recent summary of 

 this subject, with a full bibliography, is 

 •Studnifika, F. K. 1903.2. 



Excellent treatises, containing com- 

 plete bibliographies, on the development 

 of hyaline cartilage in all groups, are 

 *Novikov, M. M. 1908.1; and for the 

 chemical composition especially, irT. C. 

 C. Hansen in Anat. Hefte, 1905, Bd. 27, 

 Hft. 83, pp. 535-820, 10 pis. 



The structure of cartilage in the Cyclo- 

 stomes is most completely treated by 

 •Schaffer, J. 1896.1-1901.2, 1910.1; and 

 by •Studnieka, F. K. 1897.4,.6, 1898.1,.4. 



The histological structure in Elasmo- 

 branchs is treated by Hasse, J. C. 1879.2, 

 and by •Roth, W. 1911.1. 



Other papers on the development or struc- 

 ture of cartilage are Nardo, G. D. 1843.1, 

 1845.1; Retterer, E. 1907.1; Srdinko, 

 O. V. 1902.1; Valenciennes, A. 1851.3; 

 and Kaschkaroff, D. N. Add. 1914.2. 



The development of cartilage and carti- 

 lage cells has been especially studied in 

 connection with the development of the 

 notochord and the vertebral column. For 

 references, see under Vertebral column. 



For the chemical composition of cartilage, 

 see under Chemistry. 



Bone 



True bone is characterized by the presence 

 of included bone-cells (called also bone-cor- 

 puscles, calcigerous cells, and osteoblasts), 

 which generally occupy the lacunee of the Haver- 

 sian system and thus are included in or sur- 

 rounded by the lamellated bone matrix. It is 

 first met with in the " bony fishes " (Teleo- 

 stomes). 



Dentine, closely allied to bone, is more dense 

 and its formative cells (scleroblasts or odonto- 

 blasts) are not included in the matrix. The 

 scleroblasts, which secrete the dentine, line the 

 proximal side of the developing denticle or 

 tooth so that growth, in contrast with bone, is 

 in only one direction, i. e. outward. Dentine 

 occurs in the dermal denticles of Elasmobranchs 

 (see Dermal skeleton) and in the teeth of these . 

 fishes and all higher vertebrates (see Dentition;. 



Modern views on the histology of the bone 

 of fishes begin with the work of H. Miiller 

 (Zeitschr. wiss. Zool., Bd. ix, 1858) who first 

 correctly distinguished ossification (from calci- 

 fication) as the osteoblastic elaboration of car- 

 tilage. Williamson (W. C. 1851.1) previously 

 had considered bone to be formed by the cal- 

 cification of cartilage. 



Many genera of Teleosts possess no " bone 

 corpuscles" {i.e. lacunae occupied by osteo- 

 blasts) and tJieir bones therefore in minute 

 structiu-e much resemble dentine. This sub- 

 ject has been elaborated by Kolhker (R. A. 

 1859.1, .2) who microscopically examined more 

 than two hundred species of fishes. He found 

 that "most of the higher organized fishes are 

 amongst those with bone-corpuscles," including 

 roughly the Physostomi; Malacopterygii and 

 Ostariophysi (except Thricomycterus), and the 

 Ganoids. Those without "bone-corpuscles" 

 roughly include the Anacanthini and Pharyn- 

 gognathi, the Symbranchii, Haplomi, Plectog- 

 nathi, and all of the " Acanthopteri, with the 

 exception of the genus Thj-nnus," etc. For the 

 tissue lacking bone corpuscles, Kolliker (R. A. 

 1859.2, p. 258) used tne term " osteoides Ge- 

 webe." This work has served as the basis for 

 most modern histological researches on the 

 bones of fishes. 



The lack of bone-cells was originally 

 noted by •Queckett (J. T. 1849.1); by 

 Williamson (W. C. 1851.1, p. 693); by 

 Kolliker (R. A. 1853.1, p. 361); and by 

 Mettenheimer (C. F. 1854.1). 



Pouchet observed that, in the same in- 

 dividual, some bones may possess bone- 

 cells while others lack them. Pouchet, G. 

 1875.2. 



Other papers also containing accounts 

 of the bone-cells. Goette, A. 1878.1 (v); 

 Grassi, G. B. 1885.1; and •St^phan, P. 

 1898.2. 



The most valvxible paper on the histology 

 of the bones of fishes {in French) , contain- 

 ing a historical and a full bibliographic 

 r4sumi, is *St6phan, P. 1900.1. 



Papers treating of various phases of 

 the histology or histogenesis of the bones 

 of fishes. Aladyna, M. 1910.1, .2; •Ge- 

 genbaur. C. 1864.1, 1867.2; Goodrich, 

 E. S. 1913.2; Kostler, M. 1882.1; Renaut, 



