Normal and Reverse Pulsation of the Dorsal Vessel in Insects

Abstract

During the adult and a part of pupal stages, the dorsal vessel in insects pulsated in three phases; the rapid, the rest, and the slow phase according to its difference in pulse-frequency. In the rapid phase the pulse wave moved toward anterior along the dorsal vessel, normal pulsation, while in the slow phase toward posterior, reverse pulsation. The point of automatism, at which the pulse wave occurred, transferred after the rest phase. The transfer of the point occurred also after a lack of one pulse or a conflicting pulsation, and stopped temporarily after a fluttering or a movement of the body. The pulse wave recorded as a cardiogram showed the expanding or the contracting movement of the dorsal vessel. During the normal pulsation a rapid contraction was followed by a slow expansion, while during the reverse pulsation a rapid contraction returning back to the initial dimension occurred after an expansion in a wider degree.