RESULTS Flower buds from Artemisia spinescens with meiotic cells were collected on 10 April 1975 and 1 and 15 April 1976. The nine pairs of near equal-sized metacentric chromosomes of A. spinescens are large and provide an excellent subject for cytological analysis (Fig. 1). During interphase, a variable number of different-sized extranuclear bodies are present (Fig. 2). Their appearance and disappearance seems to coincide with that of the nucleoli. STga ereanercmerrennt aptamer cecere ee ’ es Fig. 2. Fig. 1. The normal condition of nine large metacentric bivalents in Artemisia spinescens. Small spheres are the extranucleolar bodies of Artemisia spinescens. Cells from 12 shrubs of A. spinescens were collected in the contaminated area, Site D, Plutonium Valley, Area 11, NTS, and from six shrubs about 1 km south where radiation levels were background, i.e., the control area. Of the 2,732 cells analyzed, 1,791 came from plants collected in the contaminated area and 941 came from plants in the control area. In the contaminated area 14.2% of the cells had abnormal configurations, and in the control area 3.8% were abnormal (Table 1). In Table 1 and in succeeding tables we have called "Normal" all cells which did not possess obviously aberrant configurations. Several categories of aberrants were noted. These are: eight bivalents and two univalents, multivalents of three, four, and six, fragments, dicentrics, and ring chromosomes. A large portion of the aberrations from the contaminated 357