||The experiments described in this investigation were conducted to determine the extent of variation in the yield of alkaloids that may be obtained from Veratrum callfornicum plants if they were harvested from different sites on different occasions. In particular, the study was conducted to determine the extent of variation that may be encountered in the alkaloidal yields if the plants were harvested from sites located at different altitudinal levels. Also, a study was made of the environment at the sites in which the plants grew to determine what factors may have been responsible for the variations. (A) The Analysis of Veratrum Callfornicum: The alkaloidal content of the plants was determined by means of a gravimetric analysis of a chloroform extract of the dry, powdered plant material. The results show that the alkaloidal yields extracted from plants harvested during alternate summers (1961 and 1963) did not vary significantly. Similarly, there was no significant variation in the alkaloidal yields obtained from plants harvested from within a given site (Intrasite). However, in certain cases the alkaloidal yields were significantly different. The alkaloidal yields extracted from plants exhibiting bud formation (from the Lower Site, 1961) were significantly larger than the yields obtained from the plants harvested at other times during the growing season. Also, the alkaloidal yields extracted from the rhizomes of plants (from the Lower Site, 19&3) were significantly larger than the yields obtained from the roots. (B) The Relation of the Environment to the Total Alkaloid Content of Teratrum Californlcum: The environment at the sites was studied. A survey of the slopes at the sites was conducted. Also, a mechanical analysis of the composition, a potentiometrie analysis of the pH, a spectrophotometrie measurement of the nitrate-nitrogen content, and a gravimetric measurement of the moisture content of the soils at the sites were made. In addition, the rainfall was collected and measured, and the temperature at the sites was recorded. The data show that the only significant variations occurred with respect to the pH of the soils, the moisture content of the soils, the amount of rainfall, and the temperature at the sites. A higher pH was measured at the Upper Site, but a higher soil moisture level was measured at the Lower Site, during 1963. The quantity of rainfall that occurred at the sites, during the years, and during the weekly periods varied significantly. The greatest quantity of rainfall occurred in 1961 and at the Upper Site. In addition, the average weekly mean and minimum temperatures were significantly different with the lower temperatures recorded at the Upper Site. However, the number of hours and/or days with temperatures below 40 degrees Fahrenheit did not vary significantly, (C) pie Relation of Altitude to the Total Alkaloid Content of Yeratrum Californicum Plants that had been harvested from sites located at two altitudinal levels (78OO feet and 9^00 feet above sea level) were analyzed. The data obtained show that the alkaloidal yields were significantly different and the larger yields were obtained from plants that grew at the Upper Site irrespective of the year in which the plants were harvested (1961 and 19&3) To determine the effect of the environment at the sites on the growth of this plant, their heights were measured. The plants at the Upper Site attained a greater height than did those at the Lower Site. By relating the data obtained from the analysis of the Veratrum californicum plants to the results of the environmental studies, the higher alkaloidal content and greater growth occurred in those plants that grew at the Upper Site associated with a higher soil pH, lower soil moisture content, greater rainfall, and lower average weekly mean and minimum temperatures.