"[The parasite that causes malaria] edges through the cells of the stomach wall of the mosquito and forms a cyst which grows and eventually bursts to release hundreds of "sporozoites" into the body cavity of the mosquito [...] As far as we can tell, the parasite does not harm the mosquito [...] It has always seemed to me, though, that these growing cysts [...] must at least give the mosquito something corresponding to a stomach-ache."