Abstract
The use of an acetic-haematoxylin solution in a squash method for small chromosomes is described. The concentration of the solution is 2% haematoxylin (Merck) in 45% acetic acid, the mordant is iron acetate. Three schedules are described: for Collembola or other small insects, for root tips and leaf buds, and for pollen mother cells. Hoyer's or modified Berlese's mounting media are employed to make slides permanent.