Two divergent views have been held as to the nature of the original hexapod stock.
The fat-body is therefore the seat of important metabolic processes in the hexapod body.
But the word " Insect " had become limited since the days of Linnaeus to the Hexapod Pterygote forms, to the exclusion of his Aptera.
Taken in connexion with the likeness of the young among the more generalized orders to the adults, it indicates clearly a thysanuroid starting-point for the evolution of the hexapod orders.
Scorpio is here provided with a single or double pair of renal excretory tubes, which have been identified by earlier authors with the Malpighian tubes of the Hexapod and Myriapod insects.