life cycle, except for an occasional case of nondisjunction at meiosis.The meiotic behavior of the chromosomes was studied in 100 cells from plants having only one pair of fragments. These data are summarized below and in the following paragraphs. '.92 noo 8.00 Fragments none Normal bivalents 2.4 23.44 Average chiasma frequency . (Ic, of interstitial chiasmata . % unpaired .AMONG A group of Tradescantia 2 plants collected from Gentilly, Louisiana, by Small, Anderson and Woodson, there appeared a number of individuals having in addition to the usual diploid complement of 12 chromosomes, a varying number of fragments. When a preliminary examination indicated that the number of fragments in the somatic tissue seemed to che?k with the number found at meiosis, an opportumty was presented for studying the behavior of these fragments under rather stable conditions. The technique developed by Sax and Humphrey (1934) for demonstrating the internal structure of the chromosome offers a refined method for investigating the morphology of fragments. With the ordi-The normal bivalents show the usual chiasma frenary smear methods (either aceto-carmine or per-quency, and the percentage of interstitial chiasmata rnanent) and paraffin sectioned material, the frag-characteristic of the species. The fragment chromoments appear as small, darkly-stained blobs; with somes pair almost as regularly as the normal chromothe alcohol-alkaline pre-treatment method, structural somes. The chiasma frequency per unit of pairing features that are visible in the major chromosomes length in the paired fragments is more than twice are also evident in the fragments ( fig. 3, 4).that of the normal bivalents. The fragments form The len~th of the fragments found in this group either terminal or interstitial chiasmata, although of plants IS roughly one-sixth to one-seventh that of the latter are not nearly so numerous as they are in the major chromosomes. Thev seem to be of rather the ordinary bivalents. uniform length regardless of' the number found inThe types of configurations found in the paired a single cell. In respect to their size thev differ from fragments a.re illustrated in the diagrams of figure 2, he fragments studied by Lesley and L'esley (1929) together with a regular rod bivalent. With the m the tomato. In this case, the fragments were technique used, the chromatids are well differentiated. about one-half the size of the major chromosomes. In the regular bivalents the two chromatids of each The fragments studied by Darlington (1929) in homologue are closely associated in a coiled chromo-Tradescantia and (l9;30) in Fritillaria, by Belling nema at early metaphase, and separate to form two (1925) . in Uuularia, and by Hicks and Stebbins coiled chromatids at late metaphase and anaphase.