帮忙翻译一段英语

Plant material and culture conditions have been described (7). Briefly， a diploid tissue culture line， WOO1C， of wild carrot， Daucus carota L.， was maintained in Murashige and Skoog medium supplemented with 0.1 mg of 2，4-dichlorophenoxy... Plant material and culture conditions have been described (7). Briefly， a diploid tissue culture line， WOO1C， of wild carrot， Daucus carota L.， was maintained in Murashige and Skoog medium supplemented with 0.1 mg of 2，4-dichlorophenoxyacetic acid (2，4-D). To regenerate plants from the culture， callus tissue was transferred to the same medium devoid of 2，4-D (embryogenic medium). All experiments were performed with cultures grown in liquid medium. For convenience， cultures grown in 2，4-D-containing medium are referred to as "callus cultures"， and those grown in medium without 2，4-D as "embryo cultures." The growth of callus cultures was measured by the sidearmturbidity method (7). The number of cells at any time point of growth was estimated from turbidity in a Klett-Summerson calorimeter and was expressed in arbitrary units. For example， Klett 100 corresponds to ="2 X 106 cells per ml. The relationship is linear up to Klett 150 in our Klett-Summerson colorimeter. Suspension cultures ofWOOLC cell line are normally maintained at cell densities between 106 and 107 cells per ml in 0.1 mg of 2，4-D per liter (high-density culture) in shake flasks. During a quantitative study on embryogenesis， we found that maximal embryo production can be achieved by first incubating the culture at high density in medium without 2，4-D for one generation time and then diluting it to 2-3 x 104 cells per ml (low-density culture). To compare cultures of comparable density， callus cultures and embryo cultures were subjected to the same procedure. To initiate low-density embryo or callus cultures， an 8-day-old high-density culture grown at the logarithmic phase was washed three times with fresh callus or embryogenic medium and resuspended at 8 x 105 cells per ml for one generation (3 days) in its corresponding medium. It was then diluted to 2 x 104 cells per ml; 20 ml of the culture was incubated in a plastic Petri dish (9 cm in diameter) at 240C. The morphogenetic events of the cultures were examined and photographed under a dissecting microscope. 请不要用google的那个，我看不懂~~