HEMATOPOIESIS IN LEPIDOPTERA .1. MULTIPLICATION OF CIRCULATING HEMOCYTES

Hemopoiesis in Lepidoptera is doubtlessly accomplished to a large extent by mitosis of the circulating hemocytes, but there are some anomalies with regard to certain classes. Granular hemocytes and spherule cells are the only classes that divide frequently enough to account alone for their continued increase in numbers. Prohemocytes divide frequently, but their numbers do not increase markedly. There is little doubt that they differentiate exclusively to plasmatocytes, which rarely divide themselves but continue to increase in numbers during larval life. An increase in plasmatocyte size and numbers after the 4 instar, when the mitotic index of prohemocytes is declining, suggests an alternative source. Oenocytoids never divide and undoubtedly derive from a separate source. [Euxoa declarata was used for this study.].