The Chromosomes of Rodents

Abstract
This article summarizes the essential results obtained to date by a study of the chromosomes of different rodents at the Univ. of Texas. The house mouse (worked out by E. K. Cox) has 40 spermatogonial chromosomes. The reduced number is 20, which includes a typical X-Y sex chromosome complex. The albino rat (worked out by I. Kehoe) has 42 spermatogonial chromosomes. The reduced number is 21. The indications are that here again an X-Y sex chromosome complex is present. The guinea pig (worked out by B. League) shows between 60 and 64 spermatogonial chromosomes. The best haploid counts give 30 as the reduced number. Sex chromosomes were not definitely identified. The rabbit (by the author) possesses 44 spermatogonial chromosomes; the reduced number is 22, including an X-Y complex.