REGENERATION OF TISSUES. 495 



increase of the muscle corpuscles. After being compressed, the mus- 

 cular nuclei disappear and at the same time the contractile contents 

 degenerate (Heidelberg). After several days, the sarcolemma contains 

 numerous nuclei which reproduce new muscular nuclei and the con- 

 tractile substance (Kraske, Erbkam). In fibres injured by a subcu- 

 taneous wound, Neumann found that, after 5-7 days, there was a 

 bud-like elongation of the cut ends of the fibres, at first without 

 transverse striation, but with striation ultimately. If a large extent 

 of a muscle be removed, it is replaced by cicatricial connective- 

 tissue. 



Non-Striped muscular fibres are also reproduced ; the nuclei of the 

 injured fibres divide after becoming enlarged, and exhibit a well- 

 marked intra-nuclear plexus of fibrils. The nuclei divide into two, 

 and from each of these a new fibre is formed, probably by the differen- 

 tiation of the peri-nuclear protoplasm. 



5. After a nerve is divided, the two ends do not join at once so as 

 to permit the function of the nerve to be established. On the 

 contrary, marked changes occur which are described in vol. u. If a 

 piece be cut out of a nerve-trunk, the peripheral end of the divided 

 nerve degenerates, the axial cylinder and the white substance of 

 Schwann disappear. The interval is filled up at first with juicy 

 cellular tissue. The subsequent changes are fully described in vol. ii. 

 There seems to be in peripheral nerves a continual disappearance of 

 fibres by fatty degeneration, accompanied by a consecutive formation of 

 new fibres (Sigm. Mayer). The regeneration of peripheral ganglionic 

 cells is unknown, v. Voit, however, observed that a pigeon, part of whose 

 brain was removed, had within five months reproduced a nervous mass 

 within the skull consisting of medullated nerve-fibres and nerve-cells. 

 Eichhorst and Naunyn found that in young dogs, whose spinal cord 

 was divided between the dorsal and lumbar regions, there was an ana- 

 tomical and physiological regeneration to such an extent that voluntary 

 movements could be executed. Vaulair, in the case of frogs, and 

 Masius in dogs, found that mobility or motion was first restored and 

 afterwards sensibility. Regeneration of the spinal ganglia does not 

 occur. 



6. If a portion of a secretory gland be removed, as a general rule, it 

 is not reproduced. But the bile-ducts (p. 350), and the pancreatic 

 duct may be reproduced (p. 345). According to Philippeaux and 

 Griffini, if part of the spleen be removed, it is reproduced (compare 

 p. 207). Tizzoni and Collucci observed the formation of new liver- 

 cells and bile-ducts after injury to the liver. 



7. Amongst connective-tissues, cartilage, provided its perichondrium 

 be not injured, reproduces itself by division of its cartilage cells 



