Facts and Factors of Development 



B 



FIG. i. TYPICAL TISSUE CELLS FROM DIFFERENT ORGANS. A, Epithelial 

 ells from intestine of duck embryo, showing nuclei with dark chromatic 

 lasses and clear achromatin surrounded by nuclear membrane, centrosomes 

 s two or three dark granules at the free border of the cells, and cytoplasm 

 illing the cell body. B. Two nerve cells, a. of a ringed worm, b. of a fish, 

 howing cell-body containing nucleus and nucleolus, many nturofibrils and 

 n a one nerve fiber, in b many processes, one of which (-J-) is the nerve 

 iber. C. Muscle cell from a round worm showing nucleus and cytoplasm 

 i upper part of cell and contractile fibrils in lower part. 



