Regeneration of Glands, Spleen, Lymph Glands. 245 



occurs. Alter ablation of half of the bulk of the organ new liver 

 tissue developed from the remaining- portion by luxuriant prolif- 

 eration of the hepatic cells, setting in as early as the third to the 

 fifth day; after an average of from forty to sixty days the part lost 

 was completely restored in volume and weight. It is conceivable 

 that after other local lesions liver tissue may regenerate, yet after 

 traumatic lesions or destruction of hepatic parenchyma by the pene- 

 tration of parasites nothing but cicatricial connective tissue is seen 

 at the site of the defects, always containing on microscopic examina- 

 tion decidedly proliferated bile ducts, but without evidence of 

 formation of functionally capable liver cells. This probably 

 is due to the fact that in the type of defects under con- 

 sideration the connective tissue framework has also undergone 

 pathological changes, and perfect restoration of functionating 

 parenchymatous cells can only be expected when the connective 

 tissue basic structures are in normal condition (Ribbert). The 

 enormous enlargement of the liver sometimes seen in tuberculosis 

 and echinococcus disease is apparently due not merely to the 

 foreign elements and to connective tissue hypertrophy, but may 

 possibly be dependent upon a vicarious hypertrophy or regeneration 

 of the hepatic parenchyma. 



It is not certain in case of the kidney whether epithelial cells 

 lost in consequence of inflammations and degenerations of the paren- 

 chyma can be restored completely. Lesions from infarction, suppu- 

 ration or trauma always heal by cicatrization. There may, how- 

 ever, take place a compensatory hypertrophy of adjacent tubules 

 and glomeruli to occupy the space caused by shrinkage of such 

 scars, which in a measure may compensate for the lesion. 



The tissue of the testicles and ovaries has but little regenerative 

 power ; space caused by trauma and degeneration is always filled in 

 by cicatricial tissue. On the other hand the glandular epithelium 

 of the mammary gland, thyroid, salivary and lachrymal glands is 

 capable of extensive proliferation from remaining portions of the 

 alveolar tissue, with formation of new ducts and glandular acini 

 lined with secreting epithelium. 



The spleen and lymph nodes although subject to continual 

 change of their cellular constituents and capable of originating in 

 pathological conditions a marked excess of their lymphoid tissue, 

 do not regenerate after traumatic lesions, being invariably subject 

 to cicatricial repair. 



Striated muscle, when the fibres have been partially destroyed 

 by degeneration of their substance, is able to regenerate in a certain 



