Abstract: Addition of a wide variety of organic extracts to culture media often results in favorable tissue responses in this aim we conducted an experiment on Dutura stramonium because of its essential role in medicine industry and its Alkaloids, two organic factor one thiamine-HCl and the other myo-inositol applied in this expirement, we wants to find out that the organic factors are essential in a tissue culture or not according to this aim the hypocotyls used as explants from the seeds as 3 cm length of Dutura stramonium by callus induction 100 mg L^-1 of myo-inositol, 0.5 mg L^-1 of thiamine-HCl used for organic factor. Three pieces of callus 30±0.1 g were transfer to a 100 mL Erlenmeyer flask with 50 mL of medium and incubated for 1 month in the dark at 25°C and the fresh weight of callus in each flask was determined after harvesting and comparing together for obtaining the results. Results were presented as the average of 15 replications for each treatment, the absence of thiamine-HCl or myo-inositol caused the decrease amounth in the growth of the Datura stramonium callus which been cultured on the complete medium with thiamine-HCl and myo-inositol for 8 months. Well according to this result its suggested that thiamine-HCl and myo-inositol are thought to be necessary for the growth of the callus. But the callus that had been cultured on the medium without thiamine-HCl or myoinositol for one month before the test could grow even on the medium without thiamine-HCl or myo-inositol at almost the same rate as the growth on the complete medium, From this fact the results obtained in considered to be due to a degeneration of the ability to biosynthesize thiamine-HCl and myo-inositol which occurs in the callus during its long term subculture on the medium with thiamine-HCl and myo-inositol. These degenerated abilities are restored by culturing the callus on a medium without thiamine-HCl and/or myo-inositol. The callus which lost the ability cannot grow without thiamine and requires it. But when the callus continued to becultured without thiamine, it must biosynthesize thiamine to continue to live. The ability may be restored and the callus begins to synthesize it. Once it is again supplied sufficiently by biosynthesis, the callus no longer requires added thiamine and continues to grow even without thiamine in the culture medium.