T children, each with a complex and variegated histological pattern, have exhibited sufficent consistency in that pattern to suggest a common histogenesis despite differences in site of origin and clinicobiological behavior and the variety 01 names given to these and similar tumors by other students. The 6 testicular tumors resemble those that Teoh, Steward, and Willis35 called "distinctive adenocarcinoma of the infant's testis," and ascribed to Froni the Dcpartment of Pathology and the Urologic and Pediatric Surgery Services, Kern County General Hospital, 1830 Flower St., Bakersfield, Calif.; the Deparment of Pathology, University of Southern California, Los Angeles, Calif.; the Tumor Tissue Registry of the Cancer Commission of the California Medical Association, Los Angeles, Calif .; the Pennanente Medical Group, Oakland, Calif.; and the Memorial Hospital, Exeter, Calif.We wish to record our thanks to all the individuals and institutions whose submitted c a w made this study possible. The study could never have gotten started without the co-operation of the Tumor Tissue Registry of the Cancer Commission of the California Medical Association and the eager helpfulness and encyclopedic visual memory of its registrar, Dr. WeIdon Bullock. A number of consultants have been persistent kindness itself in their considered counsel against hasty interprctations and in their willingness to thrash out debatable points. If any hasty interpretations and debatable statements have been recorded here, it is not the fault of these gentlemen. Our wannest thanks go to Dr. Arthur Calif., cases 9 and 10. hotomicrographs were made by Mr. Lloyd M a t l d y .The authors are T h e