Slide showing chart of 'Schematic representation of authors' provisional interpretation of events underlying the exhibition-time graph' relating to a Drosophila gene. Slide shows (in negative) chart of 'Schematic representation of authors' provisional interpretation of events underlying the exhibition-time graph' relating to a Drosophila (fruitfly) gene. The 'X' axis is labelled 'age of culture (days), with a scale from 0 - 23, marked in 2-day sections. The 'Y' axis label is covered by the tape and thus completely obscured. The chart has a second chart within, 'x' axis labelled 'day of emergence', 'y' axis labelled 'index of exhibition.' Title below chart reads: 'Figure 10. Schematic representation of authors' provisional interpretation of events underlying the exhibition-time graph. The exhibition-time graph is shown at the top. The bottom horizontal line shows the spread of oviposition corresponding to a particular day of emergence. The diagram shows that emergence begins about the ninth day of culture. The middle axis showing the spread of the effective period of gene action is arbitrarily placed between the scales for day of emergence and day of culture.' Late 19th to early 20th century