Incubation of living seminiferous tubules of the chinese hamster,Cricetulus barabensis, in EDTA-containing hypotonic salt solutions and subsequent Feulgen squashing gives preparations with tandemly-aligned chromosome-like structures in cells resembling spermatids. The Feulgenpositive reaction of these structures together with their morphology and number per cell (often 11-the haploid number) all suggest that they are chromosomes or parts or combinations thereof. Different possible explanations for this tandem arrangement are discussed. The most attractive of these would appear that some kind ofin vivo gemetrical ordering of chromosomes preceded that which was observed following EDTA treatment.