Mitosis in living cells 
CHESTER ARTHUR DARLING 
Practically all of the work done on the phenomena of cell 
division has been done with material that has been fixed, imbedded 
in paraffin, sectioned, and finally stained; this method has been 
subjected to various criticisms and it has been maintained that 
figures observed in the fixed and stained cells are artifacts, stages 
that do not exist in nature. Although these criticisms have been 
squarely met in many cases, undoubtedly much valuable data 
might be obtained by devoting more time to the study of the 
living cell, 
Very favorable material for studying cells in the living condition 
has been found in the young anthers of some of the maples. Twigs 
of the red maple, Acer rubrum, with flower buds were gathered on 
February 10 before any swelling of the buds had taken place. 
Twigs about 6-10 inches long were brought into the laboratory, 
Placed in a glass of water and kept near the window, the water 
was changed every day or two and the base of the stem often cut 
afresh. To examine the pollen mother cells the bud scales were 
removed and the young flowers placed on a slide and mounted in 
water; if the anthers are long enough it is best to cut them cross- 
Wise with a sharp knife; by pressing down on the cover glass the 
mass of spore mother cells are forced out of the anther and are then 
readily observed. In the case of the red maple the mother cells 
_8an to divide on February 17, one week from the time they were 
Picked from the tree, whereas those left on the tree did not divide 
Until one week later; the advantage of bringing them into the 
labor, atory is that one may examine them every day and so deter- 
mine in what Stage of growth or division the cells may be. I was 
able to observe the chromosomes in the equatorial plate, and in 
Polar View was able to count as many as 40, fixed and stained 
material showing practically the same number. An advantage in 
es cell at this stage is that the chromosomes are placed 
equally distant from each other and not drawn close together 
