Practical bacteriology, microbiology and serum therapy (medical and veterinary) : a text book for laboratory use / by A. Besson ; translated and adapted from the fifth French edition by H.J. Hutchens.
- Besson, Albert, 1868-
- Date:
- 1913
Licence: In copyright
Credit: Practical bacteriology, microbiology and serum therapy (medical and veterinary) : a text book for laboratory use / by A. Besson ; translated and adapted from the fifth French edition by H.J. Hutchens. Source: Wellcome Collection.
855/928 (page 823)
![gametogony—in contradistinction to what he believes to be simple schizogony taking place in other parts of the body (vide infra). In the lungs the trypanosome loses its undulating membrane, the two ends curve towards each other like a crescent and unite ; the female parasites then shed the blepharoplast and in both the male and female parasites the chromatin divides into eight secondary nuclei giving rise to eight merozoites, those derived from female parasites having a single nucleus, the others having both a nucleus and a blepharoplast connected by a tine thread of chromatin. These merozoites (the precursors of the gametes found in the circulating blood) then enter a red cell and develop into typical trypanosomes. These forms have been found in man, monkeys (Callithrix), cats and dogs but are very uncommon in guinea-pigs. To demonstrate the changes above described Chagas recommends that a guinea- pig should be infected with a Conorrhinus and that 1-2 c.c. of the blood of this first animal should be inoculated intra-peritoneally into a second guinea-pig -which should be killed 5 or 6 days later. In other structures.—Within the cells of certain other tissues, and notably in cardiac and striated muscular tissue and in neuroglia cells, the trypanosome multiplies, according to Chagas, by simple schizogony and gives origin to a great number of daughter parasites each having a nucleus and centrosome. In the cells of the central nervous system the young trypanosomes may proceed to the flagellated stage. The infected host cell is reduced to a mere envelope and the contents with the exception of the nucleus are destroyed. In the insect carrier.—In the mid-gut of Conorrhinus megistus the blepharo- plast approaches—and perhaps blends with—the nucleus, the undulating mem- brane disappears, the parasite becomes rounded and then multiplies rapidly bv division. The daughter parasites become flagellated, the flagellum taking- origin from the blepharoplast. In the posterior cylindrical portion of the mid-gut numerous flagellated crithidial forms are found. On two occasions Chagas found trypanosomes in the body cavity and in the salivary glands of the bug. The latter no doubt represent the forms which are inoculated when the insect bites a susceptible animal. Cultivation.—The parasite grows easily on Novy and MacNeaTs blood- agar. The cultivation forms are similar to the forms found in the bug— round forms, rapidly dividing pear-shaped forms and crithidial forms. The parasite can almost always be sub-cultivated twice. iStiology.—Chagas concludes that the bug Conorrhinus megistus does not play a purely mechanical part in the transmission of American trypanosomiasis. The bug is not infective for at least a week after the infecting meal. In Chagas’ opinion there are two different forms of development in the bug. One—the last stage of which is represented by the crithidial forms in the mid- gut and which is always seen after the insect is fed on infected blood—is without importance, the other which is very imperfectly known probably represents the true cycle. Detection of the parasite.—Blood films may be prepared and stained by Giemsa’s and Rosenbusch’s method but it is better to inoculate the blood into the peritoneal cavity of a guinea-pig. 9. Trypanosomes in birds. Danilewskv Fin 1888] was the first to give a description of trypanosomes in birds (Trypanosoma avium). Recent work has shown that, there are several species of avian trypanosomes (Laveran, Dutton and Todd, Hanna). A large number of birds are known to be infected ; for instance owls, roller-](https://iiif.wellcomecollection.org/image/b28133602_0855.jp2/full/800%2C/0/default.jpg)
