The physiology of digestion in larvae ofGastrophilus equi

Abstract

The results of the study on the digestion ofGastrophiluslarvae may be summarized as follows:(1) Pepsin-like enzymes are totally absent.(2) The salivary glands secrete a proteolytic enzyme, which has no effect on the digestion of casein, gelatine and fibrin, but acts on milk alone.(3) The midgut is capable of secreting amylolytic, proteolytic and lipolytic enzymes.(4) The body fluid contains a strong reducing substance.(5) The body fluid, as was shown by Khemnitz (1914), contains an amylolytic enzyme which is also capable of converting glycogen into glucose.(6) Free glycogen and glucose circulate in the body fluid of the larva during the prepupal and possibly the pupal stage also.(7) The larva ofGastrophilusdoes not feed on blood, but lives on the fluid material partly digested by its host in the stomach.(8) For this reason the horses do not show any symptoms even when there is a heavy infestation.