An Improved Histological Technique for Refractory Insect Brood Material in Research on Doryline Ant Behaviour

Abstract

FOR examination of the biological basis of cyclic behaviour in doryline ants, the need to have extremely thin sections of brood material in complete series covering highly limited areas of tissues, from early developmental stages to adult, has led to the improved techniques reported here. The methods of fixing, sectioning and staining have made possible the fast routine processing of otherwise difficult, refractory materials through specimens representing a wide range of body-lengths. The linear dimensions of individuals comprising the polymorphic brood in the tropical American army ant, Eciton burchelli, for example, range from that of 0.5 mm in the microlarvae to 15 mm in the semi-pupae and callows of worker majors. Throughout such a range of material we are able to obtain a complete series of uniformly thin sections for each speciment, cut at thicknesses between 4 and 7 µ at any desired angle. These thin sections, moreover, are easily mounted in series for rapid examination because these techniques furnish ribbons of tissue without the loss of sections through knife-shattering or unevenness of material usual with other techniques we have tried (for example, refs. 1 and 2). Despite the thinness of the sections, it is a rare experience to lose even one of a series through its being shattered during sectioning or in handling.