The Circulatory System of the Box Elder Bug Leptocoris trivittatus (Say)

Abstract

Relatively little is known concerning the histology and morphology of the dorsal vessel of most insects. The vessel is well described for some species, but general knowledge of its structure in various insect groups is meager. The dorsal vessel is delicate, requiring carefujl dissection and preservation. In addition, various parts, such as the ostia and the accessory pulsatile organs and membranes, when present, are difficult to observe. Some of these difficulties have been overcome in this work and thle results are here presented. Live insects were used in this study and the employment of vital stains aided immeasurably in observing and identifying the internal structures (Woolley, 1949). Dissections were made in saline solution. The entire organ or its parts were fixed in Kahle's or Carnoy's solutions, washed in alcohol and imbedded and preserved in paraffin. In addition to the gross dissections, whole mounts and serial sections were employed for details. Sections of the tissue were cut at 5, 7, and 10 microns, mounted and stained with one of the following: Hansen's Trioxyhaematin-; Heidenhain's Iron Haematoxylin; Eosin and Fast Green; Eosin and Delafield's Haematoxylin. A camera lucida was used for the histological drawings. Details were added after a careful sketch had been made of the structure to be illustrated. The drawings of the gross anatomy were made free hand.