for the clot." (Mader S.S., " Biology ," [1985], Wm. C. Brown Co: Dubuque IA, Third Edition, 1990, pp.524-525. Emphasis original) I like the ` Rube Goldberg ' touch above, that "Platelets are fragments of large bone marrow cells, called megakaryocytes, that disintegrate and discharge them into the bloodstream"! See also below