Further Studies on Sex Linked Chromosome Abnormalities

Abstract

Meiosis in male plants of Xanthorrhiza apiifolia L'Her is strictly regular and gives no indication of any abnormality or inequality among the chromosomes which might be interpreted as a sex chromosome complex. No diagnostic hybrid characteristics were found. This bears out the author's prediction and adds another case which is cited in support of the opinion that so-called sex chromosomes will not be found in monotypic species because recent hybridization has not been possible in such species. The chromosome number appears to be n-15.
Meiosis in Chamaelirium luteum L. is also quite normal, without any indication that a sex chromosome complex is present. Little evidence was found for recent hybridization of the species. The chromosome number was determined as n-12.
The origin of the meiotic chromosomes was studied in Smilax herbacea L., as a result of which the mechanism of active pairing or synapsis is questioned. The meiotic chromosomes seem to arise from a fundamentally continuous spireme which splits longitudinally and later becomes segmented into the haploid number of chromosomes. Eight of the meiotic chromosomes are associated during diakinesis in groups of two each. The chromosome number has been determined as n-13. Meiosis is normal with no trace of diagnostic hybrid characteristics.