of the body, sperm crossing or not crossing from one side of the womb to the other, and the strength or dominance of various body parts. An 18th-century French book called The art of boys suggested an extreme method of ensuring children of one sex. The author suggests that one testicle and one ovary are intended for each sex. By removing a testicle or ovary, children of the other sex can be guaranteed. Since the ancient China, Chinese people use Chinese Gender Chart to predict and select baby's gender. Chinese Gender Calendar was buried in an imperial mausoleum with a history of over 300 years. It was calculated and deduced by the ancient Chinese based on Yin-Yang, Five Elements, Eight Diagrams and time. This calendar is a simple chart who matches the day of conception of the future child with the age of the mother at the day of conception. This table contains one more chance to conceive a boy. This may reflect the current female / male ratio. Census data from India show an imbalance in sex ratios among children in the early 20th century, such disparities almost always reflect a preference for sons. In the past, son preference may have resulted in the neglect or killing of female infants. However, since the early 1980s, ultrasounds and other technologies have enabled parents to detect the sex of a foetus during prenatal screenings. Those who prefer sons may arrange to abort female foetuses. This has accelerated sex-ratio imbalances at birth in parts of the world. It is estimated that, over the past generation, tens of millions of female foetuses have been aborted. Since the 1990s, some areas have seen up to 25 per cent more male births than female births. Sperm sorting utilizes the technique of flow cytometry to analyze and 'sort' spermatozoa. During the early to mid-1980s, Dr. Glenn Spaulding was the first to sort viable whole human and animal spermatozoa using a flow cytometer, and utilized the sorted motile rabbit sperm for artificial insemination. Subsequently, the first patent application disclosing the method to sort "two viable subpopulations enriched for x- or y- sperm" was filed in April 1987 as US Application Serial Number 35,986 and later became part of US Patent 5,021,244; and the patent included the discovery of haploid expression (sex-associated membrane proteins, or SAM proteins) and the development of monoclonal antibodies to those proteins. Additional applications