. Pathogenic micro-organisms, including bacteria and Protozoa; a practical manual for students, physicians and health officers. hanging drop. Much of the life cycle may besatisfactorily demonstrated from sections of cabbage seedlings and theolder plants. There are many points, however, in the life history whichstill need explanation or corroboration. The Organism.—The roots are supposed to be infected by the flagel-lated ameboid sporozoites which leave the spore cysts in the moistearth and enter the young rootlets of the seedlings. Here they growand divide by cell bipartition and by a multiple
. Pathogenic micro-organisms, including bacteria and Protozoa; a practical manual for students, physicians and health officers. hanging drop. Much of the life cycle may besatisfactorily demonstrated from sections of cabbage seedlings and theolder plants. There are many points, however, in the life history whichstill need explanation or corroboration. The Organism.—The roots are supposed to be infected by the flagel-lated ameboid sporozoites which leave the spore cysts in the moistearth and enter the young rootlets of the seedlings. Here they growand divide by cell bipartition and by a multiple increase of the nucleusthrough a primitive karyokinesis. As these forms increase in numbersthey are supposed to fuse into a plasmodium due to overcrowding GYMNAMCEBIDA. 549 (Fig. 169 A). Following- this fusion there is a simultaneous nucleardivision by definite karyokinesis (Fig. 169 B) until the whole host cellis filled with an indefinite mass containing many tiny nuclei, which,according to Prowazek, are sexual nuclei, gametes, that fuse two bytwo, forming a copula around which a spore wall is produced. Thus, Fig. 170. Two cells infiltrated with spores of the Plasmodiophora brassicce. (Doflein.) fertilization by endogamy (sexual union between decendants of thesame cell) is accomplished. These small spores fill the dead cell of thehost (Fig. 170), and are contained in the soil where they remain untilfavorable conditions allow the infection of a new host. Bibliography. Calkins. Fertilization of Amoeba proteus. Biological Bulletin, 1907,XIII, 219. The Pathogenic Rhizopoda in Protozoology, New York and Phil., 1909. Craig. Studies upon the Amebse in the Intestines of Man. Jour, of Inf. Dis.,1908, V, 324. Councilman and Lafleur. Johns Hopkins Hospital Report, 1S91, II, 395. Dock. The Journ. of the Am. Med. Assoc, 1902, IV, 1.). Harris. On the Alterations Produced in the Large Intestines of Dogs by theAmoebae coli, etc., Philadelphia, 1901. Also, Amceinc Dysentery, Am. Me
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