Slide showing pedigree chart of haemophilia. Slide showing black and white pedigree chart of haemophilia. The three family levels are labelled I to III. Chart consists of symbols which are numbered with no corresponding explanation. Title below image reads: 'Fig. 9 - Pedigree of haemophilia, a totally sex-linked recessive, determined by a gene in the non-homologous segment of the X. I2 is a carrier. II1 is possibly normal, her children are too few to make it certain that she is. II4 is a carrier.' Late 19th - early 20th century