Journal of Applied Microscopy. 



41 



Mitosis Illustrated by Photo-Micrographs. 



WM. H. KNAPP, 

 Stewart Building, Chicago. 



It has scarcely been fifty years since the cell theory was first elucidated, 

 but within this comparatively short period it has been demonstrated that 

 the foundation of all biological problems lies in a comprehensive under- 

 standing of the cell and its vital functions. 



The growth and development of the cell has therefore been most 

 carefully studied. The subject has occupied the attention of many careful 

 investigators, and to-day, after half a century of observation, some of the 

 intricate processes of cell-division are as obscure as ever. 



One of the methods of reproduction of the cell is by mitosis, the 

 nucleus dividing first and the cell later. 



Fig. 1. 



Figure i. — This photograph is from a preparation by Dr. Charles 

 Chamberlain of the University of Chicago. The tissue is Lilium philadel- 

 phicum, showing endosperm mitosis, magnified 425 diameters. In this 

 preparation may be seen several nuclei dividing at the same time — the 

 close and loose skein or spiren, metakinesis, and also resting nuclei. In a 

 different plane, indicated by the blurred spots, are other nuclei in the 

 process of division. This slide illustrates repeated division of the nucleus 

 without cleavage of the cytoplasm. 



