66 AGRICULTURAL EXPERIMENT STATION. 



movements; hence the names 'Plasmodium' and 'Amoebnla' are 

 very appropriate. The Plasmodium remains constantly within 

 the corpuscle and feeds upon it. The haemoglobin of the corpus- 

 cle is the source of the characteristic pigment seen in the Plas- 

 modium. Eventually the corpuscle is destroyed. The applica- 

 tion of a suitable dye to a blood smear on a glass slide or cover 

 glass, stains not only the plasmodium in its entirety but also its 

 nucleus, thus demonstrating' that the malarial organism is a 

 cell. It is, in fact, a unicellular animal, a protozoan." 



The common type of malaria in New Jersey is the tertian, in 

 which the paroxysm occurs every other day. The quartan, in 

 which the chill recurs at intervals of seventy-tw'O' hours, is com- 

 paratively rare. The sestivo-autumnal fever, in wdiich the chills 

 come at irregular intervals, is an introduction from Southern 

 Europe and has undoubtedly obtained a foothold with us. 



It is now recognized that these three types of malaria are 

 caused by as many distinct species of parasites, each distin- 

 gxiished by well marked characters. Thus tertian fevers are pro- 

 duced by Plasmudiiim vknix, quartan by Plasmodium inalaricc. 

 and sestivo-autumnal by Laverania nialarice. Where, in a case 

 of tertian or quartan malaria, a chill occurs every day or at irreg- 

 ular intervals, it is due to a double infection. 



"In every fomi of malaria the chill marks an important ep(jch 

 in the life history of the parasite. At this time 'sporulation' is 

 taking place — that is to say, the plasmodia, having attained the 

 limit of their individual growth, and having used up all the 

 nourishment afforded by the corpuscle, reproduce asexually. The 

 nucleus divides into several daughter nuclei, and each of these 

 gathers to itself its due quota of the living substance, the proto- 

 plasm, of the mother cell. The enclosing membrane of the 

 used-up corpuscle now ruptures and the spores (knowni tech- 

 nically as the 'schizospores' or 'merozoits') escape intO' the blood 

 serum and thence invade other corpuscles. In doing- this they 

 disturb the temperature equilibrium of the body, and the chill 

 results. The giving of quinine is most effective at the onset oi 

 the chill, because, no doubt, the free spores in the blood are more 

 exposed tO' the poisoning action of quinine than are the plas- 

 modia in the corpuscles. If the fever is left to take its course, 

 more and more corpuscles are invaded and destroyed ; the patient 

 gets worse. Whether a condition of effective resistance is attain- 

 able — ^in other words, wdiether we may at length become immune 

 — is not known, because, of the well-nigh universal use of quinine 

 in all civilized countries, thus breaking up the fever before the 

 body has time to develop any resistant powder it may possess." 



