CYTOMORPHOSIS 27 



years ago he invented a new method to keep isolated cells 

 and pieces of tissue living in vitro. Utilizing the new method, 

 he subjected young nerve cells, neuroblasts, to observation 

 and was able to see under the microscope nerve fibers grow 

 out from the living cell. Cultures in vitro are now made 

 frequently, and we expect from the application of Harrison's 

 ingenious method many valuable discoveries. From time 

 to time we find the paradox justified which says: "New 

 methods are more important for science than new thoughts. 77 



> 





FIG. 1 6. Degenerating muscle fibers after experimental injury, a, b, after 

 3 days; c, after 8 days; d, 26 days; e, 10 days; /, 21 days; g, 43 days. 4f/er Erws* 

 Ziegler. 



The second example we get from muscles. If the fibers of 

 a skeletal muscle are mechanically injured they degenerate 

 quickly; later, however, we find new formed muscles. Here 

 the processes are of quite a peculiar sort. Every muscle 

 fiber consists chiefly of muscular substance which we can 

 easily demonstrate by the contractile fibrils. It is the 



