of sea urchin eggs, it can be demonstrated that mitosis once initiated 

 will go to completion in the presence of carbon monoxide (Swann, 

 1953). The initiation of mitosis in epidermal cells of the mouse is in- 

 hibited under anaerobic conditions or by carbon monoxide, but cells in 

 the process of active mitosis are unaffected under these same conditions 

 (Bullough, 1952). The failure of cyanide to inhibit active mitosis in 

 meristematic cells of the pea root has also been reported (Wilson and 

 Morrison, 1958). A simihu- effect of malonate and fluoracetate on mito- 

 sis in tissue culture cells was observed by Hughes (1950). In contrast, 

 chemicals known to inhibit glycolysis, such as iodoacetic acid and 

 fluoride, selectively block active mitosis in tissue cultures (Hughes, 

 1950; Pomerat and Willmer, 1939). In plant meristematic cells active 

 mitosis is also selectively inhibited by iodoacetic acid (Wilson and Mor- 

 rison, 1958). The fact that mitosis, once initiated, will continue in the 

 absence of oxygen and is inhibited by glycolytic inhibitors would seem 

 to implicate glycolysis as a possible source of energy during this particu- 

 lar phase of the mitotic cycle. While most evidence favors this view, 

 it still remains to be determined whether glycolysis is the major and 

 only energy source available to the dividing cell. 



Swann (1957) has suggested that an "energy reservoir" may be cre- 

 ated prior to cell division, which serves to supply the cell with the energy 

 necessary to carry it through the division process. If such is the case, one 

 would expect to find an increase in oxygen consumption coincident with 

 the onset of cell division. Studies of Erickson (1947) and of Stern and 

 Kirk (1948) on lily and Trillium anthers have demonstrated that such 

 a rise in rate of oxygen consumption does actually occur prior to the 

 prophase of microspore mitosis and microsporocyte meiosis, and falls 

 again as soon as cell division is initiated. Stern (1956) interpreted this 

 rise in oxygen uptake preceding mitosis as indicating an increase in 

 energy requirements of the cell in advance of active mitosis. What the 

 exact relationship is between this premitotic metabolism and the estab- 

 lishment of the so-called energy reservoir postulated by Swann is not 

 known. It is quite possible that the increased oxygen uptake preceding 

 mitosis is associated with metabolic events in the nucleus prior to the 

 onset of division rather than with establishment of an energy store to 

 be used specifically for active mitosis. As already pointed out, auto- 

 radiographic studies on nucleic acid and protein synthesis during meiosis 

 in Liliiim longiflorum indicate that active DNA and RNA synthesis oc- 

 curs in the nucleus during the premeiotic period (Taylor, 1959). The 

 synthesis of DNA is complete before the meiotic prophase is initiated, 

 while RNA synthesis ceases soon after. Protein synthesis in the nucleus 



156 / CHAPTER 6 



