Table 2.

Oil droplet colour in chick cones from previous studies and our present results (NA not applicable)

Reference	Principal	Accessory	Single	Straight	Oblique
Meyer and Cooper 1966	Golden-yellow	Greenish	Red	NA	NA
Meyer and May 1973	Golden-yellow	Yellowish-green	Red	NA	NA
Gallego et al. 1975	Yellow	Colourless	Red, yellow-green	NA	NA
Gallego 1976	Yellow-orange	Greenish	NA	Red	Green
Bowmaker and Knowles 1977	Yellow-green	Yellow-green	Red, orange-yellow, bright blue, yellow-green	NA	NA
Gayoso et al. 1978	Yellow	Yellow	NA	Red, green	Yellow
Szel et al. 1985	Yellow-green	No colour indicated	Red, yellow	NA	NA
Oishi et al. 1990	Pale green	No droplet found	Red, yellow, pale-blue, Clear	NA	NA
Our present results	Yellow and colourless	Green	NA	Red, orange, yellow, colourless	Colourless